In order to cultivate Manila clam varieties in northern China,we crossed the Dalian wild population(referred to as D)and the Weihai wild population(referred to as W)to create a 2×2 complete diallel hybrid.Ultimat...In order to cultivate Manila clam varieties in northern China,we crossed the Dalian wild population(referred to as D)and the Weihai wild population(referred to as W)to create a 2×2 complete diallel hybrid.Ultimately,we obtained two hybrid groups(D♀×W♂(DW)and W♀×D♂(WD))and two inbred groups(D♀×D♂(DD)and W♀×W♂(WW)).We measured their growth and survival during the larval and juvenile stages and compared the data between hybrid and inbred groups to study the potential heterosis of the hybrid.With the exception of slightly lower values in the WD group,fertilization and hatching rates did not differ significantly among the other groups.However,during the larval stage(days 1–15),we observed significant differences in the growth rate of Manila clam in the hybrid groups at days 1,3,and 6 of age(P<0.05).Among the groups,the clams in the DW group had the highest survival rate,which was indicative of significant heterosis.After entering the juvenile stage(days 30–120),both hybrid groups showed high heterosis in terms of growth and survival.The DW group had the greatest amount of heterosis for survival performance,and the WD group had the greatest amount of heterosis for shell length and height growth.These results indicated that this hybrid combination had great breeding potential,and provided a useful hybrid strategy for producing genetic improvements in R.philippinarum.展开更多
Previous studies have revealed that ammonia nitrogen has several adverse effects on clam Ruditapes philippinarum.However,knowledge is lacking regarding the related proteins involved in the toxicological responses,whic...Previous studies have revealed that ammonia nitrogen has several adverse effects on clam Ruditapes philippinarum.However,knowledge is lacking regarding the related proteins involved in the toxicological responses,which is vital to elucidate the underlying mechanism of ammonia nitrogen.In this study,clams R.philippinarum were exposed to ammonia nitrogen for 21 d at two environmentally relevant concentrations.The tandem mass tags approach(TMT)was applied to assay the differentially expressed proteins(DEPs)in clam gill tissues on the 3 rd and 21 st day.Finally,a total of 7263 proteins were identified.Bioinformatics analyses revealed that clam protein profiles changed in dose-and time dependent manner after ammonia nitrogen exposure.We inferred that the clams may face heavy challenges after ammonia exposure,such as unbalanced gender ratio,lysosomal disease,energy lack,neurological disorders,altered glutamine metabolism,increased lipid synthesis,and impaired immunity.Variation profiles of enzyme activities of glutaminase and glutamine synthase provided direct evidence to verify the related inference from proteome data.Most of the inferred toxic effects merit further study.This study identified important proteins related to ammonia nitrogen toxicity in the clam and indicated the severe stress of marine ammonia pollution on the healthy development of mollusc aquaculture.展开更多
The amplified fragment length polymorphism （AFLP） technology was used to analyze the genetic diversities in four natural populations of Manila clam （ Ruditapes philippinarum）, distributed in four sea areas of Chin...The amplified fragment length polymorphism （AFLP） technology was used to analyze the genetic diversities in four natural populations of Manila clam （ Ruditapes philippinarum）, distributed in four sea areas of China, i.e. , the Bohai Sea, the Huanghai Sea, the East China Sea and the South China Sea. Two hundred and sixty-four AFLP loci were analysed in 195 individuals and revealed high levels of genetic diversity. The percentage of polymorphic loci ranged from 92.13% to 96.06% and the Shannon＇ s information index was from 0.256 8 to 0. 275 6. By analyzing molecular variance （ AMOVA）, it was found that there were high levels of genetic differentiation between populations of Qingdao and the other three sea areas. Cluster analysis by Nei＇ s pairwise distances grouped specimens by geographical origin, except the population of Qingdao. A conclusion can be drawn that there are high genetic diversities in the four natural populations of Manila clam in China and some distinct differences existed among and between the four populations. The results also indicated that human cultivation activities will have great influence on the genetic structure of the population of Qingdao.展开更多
Ruditapes philippinarum,a clam that thrives in intertidal zones of various salinities,is a useful biomonitor to marine contaminants.We investigated the influence of dilution to 75% and 50% of normal seawater salinity(...Ruditapes philippinarum,a clam that thrives in intertidal zones of various salinities,is a useful biomonitor to marine contaminants.We investigated the influence of dilution to 75% and 50% of normal seawater salinity(31.1) on the responses of the digestive gland of R.philippinarum to arsenic exposure(20 μg/L),using nuclear magnetic resonance(NMR)-based metabolomics.After acute arsenic exposure for 48 h,salinity-dependent differential metabolic responses were detected.In normal seawater,arsenic exposure increased the concentrations of branched-chain amino acids,and of threonine,proline,phosphocholine and adenosine,and it decreased the levels of alanine,hypotaurine,glucose,glycogen and ATP in the digestive glands.Differential changes in metabolic biomarkers observed at lower salinity(～23.3) included elevation of succinate,taurine and ATP,and depletion of branched-chain amino acids,threonine and glutamine.Unique effects of arsenic at the lowest salinity(～15.6) included down-regulation of glutamate,succinate and ADP,and up-regulation of phosphocholine.We conclude that salinity influences the metabolic responses of this clam to arsenic.展开更多
Horizontal starch gel electrophoresis was used to investigate the genetic structure of six populations of Ruditapes philippinarum in the coast of China. Seven enzymes revealed eleven putative loci, and seven of them w...Horizontal starch gel electrophoresis was used to investigate the genetic structure of six populations of Ruditapes philippinarum in the coast of China. Seven enzymes revealed eleven putative loci, and seven of them were polymorphic, PGM^＊, MDH-1^ ＊, MDH-3^＊, LAP-1^＊, LAP-2^＊, MPI-1^＊ and MPI-2^＊. The proportions of polymorphic loci of R. philippinarum populations varied from 0.454 5 to 0.636 4. The values of observed and expected heterozygosities were from 0.039 4 to 0.154 5 and from 0.111 1 to 0.238 5, respectively. Nei＇s genetic distance varied from 0.003 3 to 0.025 3 with an average of 0.013 5. It is suggested that the genetic diversity of R. philippinarum was high.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
The marine bivalve Ruditapes philippinarum(Veneridae)has always been an economically important aquaculture species.In this study,106 831 unigenes and 2 664 SSR loci(1 locus/40 sequences)were achieved from the de novo ...The marine bivalve Ruditapes philippinarum(Veneridae)has always been an economically important aquaculture species.In this study,106 831 unigenes and 2 664 SSR loci(1 locus/40 sequences)were achieved from the de novo assembly transcriptome.Among all the SSRs,tri-nucleotides(46.40%)was the most,followed by di-nucleotides(32.43%).Meanwhile,AAC/GTT(19.82%)was the most common SSR loci searched.After polymorphism detection using 32 wild R.philippinarum individuals,34 polymorphic and 3 monomorphic SSR loci were screened,and the genetic index of them was calculated.The results show that PIC of 30 polymorphic SSR loci was at medium and high levels(PIC>0.25).However,there were five SSR polymorphic loci(e.g.MG871423,MG871428,MG871429,MG871434,MG871435)deviating from the Hardy-Weinberg equilibrium after the Bonferroni correction(adjusted P=0.001 471).The Na value(number of alleles per locus)ranged from 2 to 7.In addition,the Ho(observed heterozygosities)and He(expected heterozygosities)were 0.100 0-1.000 0 and 0.191 3-0.723 6,respectively.Therefore,RNA-Seq was shown as a fast and cost-effective method for genic SSR development in non-model species.Meanwhile,the 37 loci from R.philippinarum will further enrich the genetic information and advance the population conservation and restoration.展开更多
The typical organic pollutant polycyclic aromatic hydrocarbon(PAH) anthracene was selected as a contaminant to investigate its eff ects on the activities of superoxide dismutase(SOD), catalase(CAT) and glutathione per...The typical organic pollutant polycyclic aromatic hydrocarbon(PAH) anthracene was selected as a contaminant to investigate its eff ects on the activities of superoxide dismutase(SOD), catalase(CAT) and glutathione peroxidase(GSH-Px) in the clam Ruditapes philippinarum. The results show that SOD, CAT and GSH-Px had diff erent induction and inhibition reactions to anthracene stress, and that three diff erent organs in R. philippinarum(visceral mass, muscle tissue and mantle) had diff erent sensitivities to anthracene stress. This study suggest that SOD activities of the visceral mass, CAT activitities of the mantle and the visceral mass, and GSH-Px activity of the muscle tissue could be used as sensitive indicators of anthracene stress in R. philippinarum.展开更多
This study analyzed the function of different glutathione S-transferase(GST)isoforms and detoxification metabolism responses in Manila clam,Ruditapes philippinarum,exposed to 4 kinds of polycyclic aromatic hydrocarbon...This study analyzed the function of different glutathione S-transferase(GST)isoforms and detoxification metabolism responses in Manila clam,Ruditapes philippinarum,exposed to 4 kinds of polycyclic aromatic hydrocarbons(PAHs)single,and their mixtures for 15 days under laboratory conditions.13 kinds of GSTs in R.philippinarum were classified,and the results of tissue distribution indicated that 12 kinds of GSTs(except GST sigma 3)expressed most in digestive glands.We detected the m RNA expression levels of aryl hydrocarbon receptor signaling pathway,and detoxification system in digestive glands of clams exposed to benzo[a]pyrene(Ba P),chrysene(CHR),benzo[a]anthracene(Ba A),benzo[b]fluoranthene(Bb F),and Ba P+CHR+Ba A+Bb F,respectively.Among these genes,we selected GST-sigma,GST-omega and GST-pi as potential indicators to Ba P;GST-sigma,GST-A and GST-rho to CHR;GST-pi,GST-sigma,GST-A,GST-rho and GST-microsomal to Ba A;GST-theta and GST-mu to Bb F;while GST-pi and GST-mu to the mixture of Ba P,CHR,Ba A and Bb F.Additionally,the bioaccumulation of PAHs in tissues increased remarkably over time,and showed an obvious doseeffect.Under the same concentration,the bioaccumulation in single exposure group was higher than that in mixture group,and the bioaccumulation of PAHs in tissues with different concentrations of stress was irregular.The results revealed the metabolic differences and bioaccumulation rules in clams exposed to four kinds of PAHs,and provided more valuable information for the PAHs risk assessment.展开更多
Manila clam （Ruditapes philippinarum） was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010.The annual variations of major elemental composition,organic content,fatness and...Manila clam （Ruditapes philippinarum） was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010.The annual variations of major elemental composition,organic content,fatness and element ratio of Manila clam were examined.The element removal effect of clam farming in Jiaozhou Bay was analyzed based on natural mortality and clam harvest.The results indicated that the variation trend of carbon content in shell （Cshell） was similar to that in clam （Cclam）.Such a variation was higher in summer and autumn than in other seasons,which ranged from 9.10±0.13 to 10.38 ± 0.09 mmol g^-1 and from 11.28 ±0.29 to 12.36±0.06 mmol g 1,respectively.Carbon content of flesh （Cflnesh） showed an opposite variation trend to that of shell in most months,varying from 29.42 ± 0.05 to 33.64 ± 0.62 mmol g^-1.Nitrogen content of shell （Nshell） and flesh （Nflesh） changed seasonally,which was relatively low in spring and summer.Nshell and Nflesh varied from 0.07 ±0.009 to 0.14±0.009 mmol g^-1 and from 5.46 ± 0.12 to 7.39 ± 0.43 mmol g^-1,respectively.Total nitrogen content of clam ranged from 0.50 ± 0.003 to 0.76 ± 0.10 mmol g^-1 with a falling tend except for a high value in March 2010.Phosphorus content of clam （Nclam） fluctuated largely,while phosphorus content of shell （Pshell） was less varied than that of flesh （Pflesh）.Pshell varied from 0.006±0.001 to 0.016±0.001 mmol g^-1; while Pflesh fluctuated between 0.058±0.017 and 0.293±0.029mmolg^-1.Pclam ranged from 0.015±0.002 to 0.041 ±0.006mmolg^-1.Carbon and nitrogen content were slightly affected by shell length,width or height.Elemental contents were closely related to the reproduction cycle.The removal amounts of carbon,nitrogen and phosphorus from clam harvest and natural death in Jiaozhou Bay were 2.92× 10^4t,1420t and 145 t,respectively.The nutrient removal may aid to reduce the concentrations of nitrogen and phosphorus,the main causes of eutrophication,and to maintain the ecosystem health of Jiaozhou Bay.展开更多
The bivalve Ruditapes philippinarum is not only one of the main mollusc species in the west Pacific Ocean, but also one of the main species for aquaculture in China. Knowledge of growth of the R. philippinarum shell w...The bivalve Ruditapes philippinarum is not only one of the main mollusc species in the west Pacific Ocean, but also one of the main species for aquaculture in China. Knowledge of growth of the R. philippinarum shell will improve our understanding of the shell as an environmental archive. It is also useful for the aquaculture of R. philippinarum. In this research, a hanging box culture method was introduced in the culture of R. philippinarum. The bivalves were cultured for 126 days, from March 31 to August 3, 2002. The average growth rates of shell width, height, and thickness were 0.069, 0.046, and 0.032 mm/d, respectively. The mean increase of average individual wet mass was 0.028 g/d. The largest growth rates of both shell and average individual wet mass occurred in June, indicating that water temperature and bivalve reproduction were 2 important factors. The shell morphology underwent significant changes with shell growth. The ratio of height to thickness (value of B/C) shifted 1.58 in the first 60 days to 1.54 in the last 30 days, which was resulted from the change in major shell growth direction. Periodic changes in the B/C ratio led to corrugated shell form, which could be used to determine the age of the shell.展开更多
Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowin...Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment.In order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without sediments.In the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or whitened.SEM observations confirmed the changes of the external shell surface.In the second experiment(170 d),sediment was placed at the bottom of each exposure chamber.The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment.Although the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions.Our results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.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
The mRNA differential display (DDRT-PCR) technique was adopted to find out the genes related tosettlement metamorphosis development process of Ruditapes philippinarum larvae.In this study,we haveobtained three hundred...The mRNA differential display (DDRT-PCR) technique was adopted to find out the genes related tosettlement metamorphosis development process of Ruditapes philippinarum larvae.In this study,we haveobtained three hundred and forty-six amplification bands in total from pediveliger larvae,veliger larvae,eye spot larvae and post-larvae.Sixty-five out of three hundred and forty-six bands are distinctly differen-tial display from band pattern,which can be put into four groups,standing for different expression char-acters.Sixteen differential display bands were cloned,sequenced and analyzed and nine different se-quences are obtained in the study.Three sequences have higher similarity to the cDNAs deposited indatabase and three are very similar to the rDNA of other species,considered as the rDNA of Ruditapesphilippinarum.The rest three sequences are found to be novel sequences after analyzed.Their accessionnumbers are AY916799,AY916798,and AY916797 respectively.We thought the novel sequences arepossibly relevant to the early embryo development of Ruditapes philippinarum larvae and can provide somefundamental understandings that are helpful for the improvement of scallop seed raising industry.展开更多
The male gametogenic cycle, spawning season, first sexual maturity, and the biological minimum size in male Ruditapes philippinarum were investigated by qualitative and quantitative reproductive analyses. In the study...The male gametogenic cycle, spawning season, first sexual maturity, and the biological minimum size in male Ruditapes philippinarum were investigated by qualitative and quantitative reproductive analyses. In the study of the male gametogenic cycle by qualitative histological analysis, the gametogenic cycle in male individuals can be classified into five successive stages： （1） early active stage, （2） late active stage, （3） ripe stage, （4） partially spawned stage, and （5） spent and inactive stage. Monthly changes in the gonad index in males measured by qualitative analysis showed a similar pattern to the male gametogenic cycle. In the study of the male gametogenic cycle by quantitative statistical analysis, monthly changes in the portions （%） of areas occupied by the testis areas to total tissue areas showed a rapid increase in March, and reached the maximum in May-June. And also monthly changes in the portions （%） of areas occupied by the spermatogenic stages to the testis area showed a maximum in May and gradually decreased from June to October. Therefore, this species showed a unimodal gametogenic cycle during the year, and the number of spawning seasons occurred once per year, from June to October, with a peak spawning between July and August. The percentage at the first sexual maturity of male clams ranging from 15.1-20.0 mm in shell length was 64.7%, and that of all individuals ranging from over 25.1 mm in shell length was 100%. The biological minimum size （shell lengths at 50% of sexual maturity （RMs0）） of male mature clams that was fitted to an exponential equation was 17.16 mm （considered to be 1 year old）. Because harvesting clams less than 17.16 mm in shell length could potentially cause a drastic reduction in recruitment, a measure indicating a prohibitory fishing size should be enacted for adequate fisheries management.展开更多
[Objectives]The antibacterial mechanism of protein hydrolysate from Ruditapes philippinarum(named RPPH)was studied in this article.[Methods]The integrity of bacteria's wall and membrane was determined by some trad...[Objectives]The antibacterial mechanism of protein hydrolysate from Ruditapes philippinarum(named RPPH)was studied in this article.[Methods]The integrity of bacteria's wall and membrane was determined by some traditional ways.[Results]The growth of Staphylococcus aureus and Bacillus subtilis were inhibited by RPPH in the logarithmic phase.The activity of alkaline phosphatase could be detected in the culture solution.The results showed that the protein content and the conductivity of two kinds of bacteria increased with the extension of incubation time.The results of scanning electron microscope revealed that it emerged the phenomenon of agglomeration with the extension of response time in the culture solution of S.aureus,and the cell shape became irregular,a large number of cells stuck together,afterwards intracellular material was released from bacteria,and the boundaries among cells completely disappeared.The cell surface of B.subtilis became rough,the cells began to adhere,intercellular boundaries became blurred,subsequently cells broke,and then intracellular material leaked out after treating for 9 h.The form of B.subtilis could be roughly identified from the remnants of the bacterial debris,and most of the bacteria had been completely cracked and died.Transmission electron microscope results showed that the surface of S.aureus became rough,with uneven distribution of cytoplasm,and darker substances appeared in the middle,followed by leakage of large numbers of intracellular material.Massive cells became dead when treating for 9 h.B.subtilis cells began to shrink,and cytoplasm was distributed unevenly.The significant phenomenon of plasmolysis and rupture of cell wall could be observed.Afterwards,intracellular material spilled out,only the residual and ambiguity nucleoplasm area could be seen,and cells were killed.[Conclusions]Therefore,it was speculated that the RPPH could destroy cell wall and membrane of the two kinds of bacteria,change the permeability of cells membrane,result in the leakage of intracellular substances and enter within the bacterial cells to affect their normal physiological metabolism which led to death.展开更多
The shell surface of Manila clam(Ruditapes philippinarum)has a variety of colors and stripes,with diverse shell color polymorphism.As an important trait of economic shellfish,shell color plays an important role in the...The shell surface of Manila clam(Ruditapes philippinarum)has a variety of colors and stripes,with diverse shell color polymorphism.As an important trait of economic shellfish,shell color plays an important role in the selection breeding of shellfish species.In this study,we extracted melanin from the shell and mantle of R.philippinarum by the hydrochloric acid method and measured the melanin content by spectrophotometry.The absorption spectrum of melanin and its absorption peak at 350 nm absorbance was determined.We found significant differences in the melanin content of clams with dark strain and light strain,as well as four different shell colors.Moreover,we further detected the activities of enzymes related to melanin synthesis in R.philippinarum mantle,such as tyrosinase(TYR),tyrosine hydroxylase(TH),dopa decarboxylase(DDC),N-acetyltransferase(NAT),and N-β-alanyldopamine(NBAD)in the mantle of R.philippinarum.The results showed that the activities of TYR,TH,DDC and NAT were positively correlated with the content of melanin.However,the activity of NBAD was negatively correlated with the content of melanin.Altogether,these results indicating that these enzymes are involved in the regulation of the melanogenesis pathway of R.philippinarum.This study provides valuable information for further research on shell color genetic mechanism and breeding of R.philippinarum.展开更多
基金sponsored by the the Outstanding Young Scientific and Technological Talents Foundation of Dalian(No.2024RJ014)the Research Project of Liaoning Provincial Department of Education(No.LJ212410158027)+1 种基金the Research Projects of Undergraduate Universities in Liaoning Province(No.2024JBZDZ003)the Liaoning Revitalization Talents Program(No.XLYC2403165).
文摘In order to cultivate Manila clam varieties in northern China,we crossed the Dalian wild population(referred to as D)and the Weihai wild population(referred to as W)to create a 2×2 complete diallel hybrid.Ultimately,we obtained two hybrid groups(D♀×W♂(DW)and W♀×D♂(WD))and two inbred groups(D♀×D♂(DD)and W♀×W♂(WW)).We measured their growth and survival during the larval and juvenile stages and compared the data between hybrid and inbred groups to study the potential heterosis of the hybrid.With the exception of slightly lower values in the WD group,fertilization and hatching rates did not differ significantly among the other groups.However,during the larval stage(days 1–15),we observed significant differences in the growth rate of Manila clam in the hybrid groups at days 1,3,and 6 of age(P<0.05).Among the groups,the clams in the DW group had the highest survival rate,which was indicative of significant heterosis.After entering the juvenile stage(days 30–120),both hybrid groups showed high heterosis in terms of growth and survival.The DW group had the greatest amount of heterosis for survival performance,and the WD group had the greatest amount of heterosis for shell length and height growth.These results indicated that this hybrid combination had great breeding potential,and provided a useful hybrid strategy for producing genetic improvements in R.philippinarum.
基金Supported by the Natural Science Foundation of Shandong Province(No.ZR 2023 MD 059)the National Natural Science Foundation of China(No.41876135)。
文摘Previous studies have revealed that ammonia nitrogen has several adverse effects on clam Ruditapes philippinarum.However,knowledge is lacking regarding the related proteins involved in the toxicological responses,which is vital to elucidate the underlying mechanism of ammonia nitrogen.In this study,clams R.philippinarum were exposed to ammonia nitrogen for 21 d at two environmentally relevant concentrations.The tandem mass tags approach(TMT)was applied to assay the differentially expressed proteins(DEPs)in clam gill tissues on the 3 rd and 21 st day.Finally,a total of 7263 proteins were identified.Bioinformatics analyses revealed that clam protein profiles changed in dose-and time dependent manner after ammonia nitrogen exposure.We inferred that the clams may face heavy challenges after ammonia exposure,such as unbalanced gender ratio,lysosomal disease,energy lack,neurological disorders,altered glutamine metabolism,increased lipid synthesis,and impaired immunity.Variation profiles of enzyme activities of glutaminase and glutamine synthase provided direct evidence to verify the related inference from proteome data.Most of the inferred toxic effects merit further study.This study identified important proteins related to ammonia nitrogen toxicity in the clam and indicated the severe stress of marine ammonia pollution on the healthy development of mollusc aquaculture.
文摘The amplified fragment length polymorphism （AFLP） technology was used to analyze the genetic diversities in four natural populations of Manila clam （ Ruditapes philippinarum）, distributed in four sea areas of China, i.e. , the Bohai Sea, the Huanghai Sea, the East China Sea and the South China Sea. Two hundred and sixty-four AFLP loci were analysed in 195 individuals and revealed high levels of genetic diversity. The percentage of polymorphic loci ranged from 92.13% to 96.06% and the Shannon＇ s information index was from 0.256 8 to 0. 275 6. By analyzing molecular variance （ AMOVA）, it was found that there were high levels of genetic differentiation between populations of Qingdao and the other three sea areas. Cluster analysis by Nei＇ s pairwise distances grouped specimens by geographical origin, except the population of Qingdao. A conclusion can be drawn that there are high genetic diversities in the four natural populations of Manila clam in China and some distinct differences existed among and between the four populations. The results also indicated that human cultivation activities will have great influence on the genetic structure of the population of Qingdao.
基金Supported by the National Natural Science Foundation of China(No.41106102)Natural Science Foundation of Shandong Province(No.ZR2009CZ008)the 100 Talents Program of Chinese Academy of Sciences
文摘Ruditapes philippinarum,a clam that thrives in intertidal zones of various salinities,is a useful biomonitor to marine contaminants.We investigated the influence of dilution to 75% and 50% of normal seawater salinity(31.1) on the responses of the digestive gland of R.philippinarum to arsenic exposure(20 μg/L),using nuclear magnetic resonance(NMR)-based metabolomics.After acute arsenic exposure for 48 h,salinity-dependent differential metabolic responses were detected.In normal seawater,arsenic exposure increased the concentrations of branched-chain amino acids,and of threonine,proline,phosphocholine and adenosine,and it decreased the levels of alanine,hypotaurine,glucose,glycogen and ATP in the digestive glands.Differential changes in metabolic biomarkers observed at lower salinity(～23.3) included elevation of succinate,taurine and ATP,and depletion of branched-chain amino acids,threonine and glutamine.Unique effects of arsenic at the lowest salinity(～15.6) included down-regulation of glutamate,succinate and ADP,and up-regulation of phosphocholine.We conclude that salinity influences the metabolic responses of this clam to arsenic.
文摘Horizontal starch gel electrophoresis was used to investigate the genetic structure of six populations of Ruditapes philippinarum in the coast of China. Seven enzymes revealed eleven putative loci, and seven of them were polymorphic, PGM^＊, MDH-1^ ＊, MDH-3^＊, LAP-1^＊, LAP-2^＊, MPI-1^＊ and MPI-2^＊. The proportions of polymorphic loci of R. philippinarum populations varied from 0.454 5 to 0.636 4. The values of observed and expected heterozygosities were from 0.039 4 to 0.154 5 and from 0.111 1 to 0.238 5, respectively. Nei＇s genetic distance varied from 0.003 3 to 0.025 3 with an average of 0.013 5. It is suggested that the genetic diversity of R. philippinarum was high.
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 National Natural Science Foundation of China(No.31272668)the Natural Science Foundation of Fujian Province(No.2017J01638)
文摘The marine bivalve Ruditapes philippinarum(Veneridae)has always been an economically important aquaculture species.In this study,106 831 unigenes and 2 664 SSR loci(1 locus/40 sequences)were achieved from the de novo assembly transcriptome.Among all the SSRs,tri-nucleotides(46.40%)was the most,followed by di-nucleotides(32.43%).Meanwhile,AAC/GTT(19.82%)was the most common SSR loci searched.After polymorphism detection using 32 wild R.philippinarum individuals,34 polymorphic and 3 monomorphic SSR loci were screened,and the genetic index of them was calculated.The results show that PIC of 30 polymorphic SSR loci was at medium and high levels(PIC>0.25).However,there were five SSR polymorphic loci(e.g.MG871423,MG871428,MG871429,MG871434,MG871435)deviating from the Hardy-Weinberg equilibrium after the Bonferroni correction(adjusted P=0.001 471).The Na value(number of alleles per locus)ranged from 2 to 7.In addition,the Ho(observed heterozygosities)and He(expected heterozygosities)were 0.100 0-1.000 0 and 0.191 3-0.723 6,respectively.Therefore,RNA-Seq was shown as a fast and cost-effective method for genic SSR development in non-model species.Meanwhile,the 37 loci from R.philippinarum will further enrich the genetic information and advance the population conservation and restoration.
基金Supported by the Joint Funds of the National Natural Science Foundation of China and the Marine Science Research Center of People’s Government of Shandong Province(No.U1406403)
文摘The typical organic pollutant polycyclic aromatic hydrocarbon(PAH) anthracene was selected as a contaminant to investigate its eff ects on the activities of superoxide dismutase(SOD), catalase(CAT) and glutathione peroxidase(GSH-Px) in the clam Ruditapes philippinarum. The results show that SOD, CAT and GSH-Px had diff erent induction and inhibition reactions to anthracene stress, and that three diff erent organs in R. philippinarum(visceral mass, muscle tissue and mantle) had diff erent sensitivities to anthracene stress. This study suggest that SOD activities of the visceral mass, CAT activitities of the mantle and the visceral mass, and GSH-Px activity of the muscle tissue could be used as sensitive indicators of anthracene stress in R. philippinarum.
基金supported by the Key Technology Research and Development Program of Shandong Province(No.2018GHY115007)。
文摘This study analyzed the function of different glutathione S-transferase(GST)isoforms and detoxification metabolism responses in Manila clam,Ruditapes philippinarum,exposed to 4 kinds of polycyclic aromatic hydrocarbons(PAHs)single,and their mixtures for 15 days under laboratory conditions.13 kinds of GSTs in R.philippinarum were classified,and the results of tissue distribution indicated that 12 kinds of GSTs(except GST sigma 3)expressed most in digestive glands.We detected the m RNA expression levels of aryl hydrocarbon receptor signaling pathway,and detoxification system in digestive glands of clams exposed to benzo[a]pyrene(Ba P),chrysene(CHR),benzo[a]anthracene(Ba A),benzo[b]fluoranthene(Bb F),and Ba P+CHR+Ba A+Bb F,respectively.Among these genes,we selected GST-sigma,GST-omega and GST-pi as potential indicators to Ba P;GST-sigma,GST-A and GST-rho to CHR;GST-pi,GST-sigma,GST-A,GST-rho and GST-microsomal to Ba A;GST-theta and GST-mu to Bb F;while GST-pi and GST-mu to the mixture of Ba P,CHR,Ba A and Bb F.Additionally,the bioaccumulation of PAHs in tissues increased remarkably over time,and showed an obvious doseeffect.Under the same concentration,the bioaccumulation in single exposure group was higher than that in mixture group,and the bioaccumulation of PAHs in tissues with different concentrations of stress was irregular.The results revealed the metabolic differences and bioaccumulation rules in clams exposed to four kinds of PAHs,and provided more valuable information for the PAHs risk assessment.
基金funded by the Public Science and Technology Research Funds Projects of Ocean (Grant No.200805066)National Natural Science Foundation of China (Grant No.41006083)Shandong Provincial Natural Science Foundation, China (Grant No.ZR2010DQ026)
文摘Manila clam （Ruditapes philippinarum） was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010.The annual variations of major elemental composition,organic content,fatness and element ratio of Manila clam were examined.The element removal effect of clam farming in Jiaozhou Bay was analyzed based on natural mortality and clam harvest.The results indicated that the variation trend of carbon content in shell （Cshell） was similar to that in clam （Cclam）.Such a variation was higher in summer and autumn than in other seasons,which ranged from 9.10±0.13 to 10.38 ± 0.09 mmol g^-1 and from 11.28 ±0.29 to 12.36±0.06 mmol g 1,respectively.Carbon content of flesh （Cflnesh） showed an opposite variation trend to that of shell in most months,varying from 29.42 ± 0.05 to 33.64 ± 0.62 mmol g^-1.Nitrogen content of shell （Nshell） and flesh （Nflesh） changed seasonally,which was relatively low in spring and summer.Nshell and Nflesh varied from 0.07 ±0.009 to 0.14±0.009 mmol g^-1 and from 5.46 ± 0.12 to 7.39 ± 0.43 mmol g^-1,respectively.Total nitrogen content of clam ranged from 0.50 ± 0.003 to 0.76 ± 0.10 mmol g^-1 with a falling tend except for a high value in March 2010.Phosphorus content of clam （Nclam） fluctuated largely,while phosphorus content of shell （Pshell） was less varied than that of flesh （Pflesh）.Pshell varied from 0.006±0.001 to 0.016±0.001 mmol g^-1; while Pflesh fluctuated between 0.058±0.017 and 0.293±0.029mmolg^-1.Pclam ranged from 0.015±0.002 to 0.041 ±0.006mmolg^-1.Carbon and nitrogen content were slightly affected by shell length,width or height.Elemental contents were closely related to the reproduction cycle.The removal amounts of carbon,nitrogen and phosphorus from clam harvest and natural death in Jiaozhou Bay were 2.92× 10^4t,1420t and 145 t,respectively.The nutrient removal may aid to reduce the concentrations of nitrogen and phosphorus,the main causes of eutrophication,and to maintain the ecosystem health of Jiaozhou Bay.
基金Supported by the Natural Science Foundation of Shandong Province (No. Y2001E02)the National Natural Science Foundation of China (No. 40676035).
文摘The bivalve Ruditapes philippinarum is not only one of the main mollusc species in the west Pacific Ocean, but also one of the main species for aquaculture in China. Knowledge of growth of the R. philippinarum shell will improve our understanding of the shell as an environmental archive. It is also useful for the aquaculture of R. philippinarum. In this research, a hanging box culture method was introduced in the culture of R. philippinarum. The bivalves were cultured for 126 days, from March 31 to August 3, 2002. The average growth rates of shell width, height, and thickness were 0.069, 0.046, and 0.032 mm/d, respectively. The mean increase of average individual wet mass was 0.028 g/d. The largest growth rates of both shell and average individual wet mass occurred in June, indicating that water temperature and bivalve reproduction were 2 important factors. The shell morphology underwent significant changes with shell growth. The ratio of height to thickness (value of B/C) shifted 1.58 in the first 60 days to 1.54 in the last 30 days, which was resulted from the change in major shell growth direction. Periodic changes in the B/C ratio led to corrugated shell form, which could be used to determine the age of the shell.
基金Supported by the earmarked fund for Modern Agro-industry Technology Research System(No.CARS-48)
文摘Although the impact of ocean acidification on marine bivalves has been previously investigated under mainly controlled laboratory conditions,it is still unclear whether the impact of acidification on sediment-burrowing species differs between those within or without sediment.In order to fill this gap in our knowledge,we compared shell properties of the infaunal Manila clam(Ruditapes philippinarum)exposed to three pH concentrations(7.4,7.7,and 8.0),within and without sediments.In the first experiment(140 d),clams were exposed to seawater in an acidification system without sediment.A decrease in shell weight corresponding to the increase in dissolution rate was observed in the group ofpH 7.4,at which shell color disappeared or whitened.SEM observations confirmed the changes of the external shell surface.In the second experiment(170 d),sediment was placed at the bottom of each exposure chamber.The effects were found obvious in shell dissolution rate and shell color in the shell specimens exposed to overlying seawater but not found in the shell specimens exposed to sediment.Although the experimental period was longer in the second experiment,shell specimens in the first experiment were more seriously damaged than those in the second experiment under acidic seawater conditions.Our results,in relation to the defense function of the shell,show that marine bivalves in burrowing behavior are more adaptable to seawater acidification than those who do not burrow into sediment.
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.
基金the National High Technology Research and Development Programme of China(No.2002AA603015)
文摘The mRNA differential display (DDRT-PCR) technique was adopted to find out the genes related tosettlement metamorphosis development process of Ruditapes philippinarum larvae.In this study,we haveobtained three hundred and forty-six amplification bands in total from pediveliger larvae,veliger larvae,eye spot larvae and post-larvae.Sixty-five out of three hundred and forty-six bands are distinctly differen-tial display from band pattern,which can be put into four groups,standing for different expression char-acters.Sixteen differential display bands were cloned,sequenced and analyzed and nine different se-quences are obtained in the study.Three sequences have higher similarity to the cDNAs deposited indatabase and three are very similar to the rDNA of other species,considered as the rDNA of Ruditapesphilippinarum.The rest three sequences are found to be novel sequences after analyzed.Their accessionnumbers are AY916799,AY916798,and AY916797 respectively.We thought the novel sequences arepossibly relevant to the early embryo development of Ruditapes philippinarum larvae and can provide somefundamental understandings that are helpful for the improvement of scallop seed raising industry.
文摘The male gametogenic cycle, spawning season, first sexual maturity, and the biological minimum size in male Ruditapes philippinarum were investigated by qualitative and quantitative reproductive analyses. In the study of the male gametogenic cycle by qualitative histological analysis, the gametogenic cycle in male individuals can be classified into five successive stages： （1） early active stage, （2） late active stage, （3） ripe stage, （4） partially spawned stage, and （5） spent and inactive stage. Monthly changes in the gonad index in males measured by qualitative analysis showed a similar pattern to the male gametogenic cycle. In the study of the male gametogenic cycle by quantitative statistical analysis, monthly changes in the portions （%） of areas occupied by the testis areas to total tissue areas showed a rapid increase in March, and reached the maximum in May-June. And also monthly changes in the portions （%） of areas occupied by the spermatogenic stages to the testis area showed a maximum in May and gradually decreased from June to October. Therefore, this species showed a unimodal gametogenic cycle during the year, and the number of spawning seasons occurred once per year, from June to October, with a peak spawning between July and August. The percentage at the first sexual maturity of male clams ranging from 15.1-20.0 mm in shell length was 64.7%, and that of all individuals ranging from over 25.1 mm in shell length was 100%. The biological minimum size （shell lengths at 50% of sexual maturity （RMs0）） of male mature clams that was fitted to an exponential equation was 17.16 mm （considered to be 1 year old）. Because harvesting clams less than 17.16 mm in shell length could potentially cause a drastic reduction in recruitment, a measure indicating a prohibitory fishing size should be enacted for adequate fisheries management.
基金Supported by National Natural Science Fund of China(31301587)
文摘[Objectives]The antibacterial mechanism of protein hydrolysate from Ruditapes philippinarum(named RPPH)was studied in this article.[Methods]The integrity of bacteria's wall and membrane was determined by some traditional ways.[Results]The growth of Staphylococcus aureus and Bacillus subtilis were inhibited by RPPH in the logarithmic phase.The activity of alkaline phosphatase could be detected in the culture solution.The results showed that the protein content and the conductivity of two kinds of bacteria increased with the extension of incubation time.The results of scanning electron microscope revealed that it emerged the phenomenon of agglomeration with the extension of response time in the culture solution of S.aureus,and the cell shape became irregular,a large number of cells stuck together,afterwards intracellular material was released from bacteria,and the boundaries among cells completely disappeared.The cell surface of B.subtilis became rough,the cells began to adhere,intercellular boundaries became blurred,subsequently cells broke,and then intracellular material leaked out after treating for 9 h.The form of B.subtilis could be roughly identified from the remnants of the bacterial debris,and most of the bacteria had been completely cracked and died.Transmission electron microscope results showed that the surface of S.aureus became rough,with uneven distribution of cytoplasm,and darker substances appeared in the middle,followed by leakage of large numbers of intracellular material.Massive cells became dead when treating for 9 h.B.subtilis cells began to shrink,and cytoplasm was distributed unevenly.The significant phenomenon of plasmolysis and rupture of cell wall could be observed.Afterwards,intracellular material spilled out,only the residual and ambiguity nucleoplasm area could be seen,and cells were killed.[Conclusions]Therefore,it was speculated that the RPPH could destroy cell wall and membrane of the two kinds of bacteria,change the permeability of cells membrane,result in the leakage of intracellular substances and enter within the bacterial cells to affect their normal physiological metabolism which led to death.
基金supported by the Dalian Science and Technology Innovation Fund Project(2022JJ12SN054)sponsored by the Scientific Research Funding from Liaoning Provincial Department of Education(LJKZ0701+1 种基金QL201703)China Agriculture Research System of MOF and MARA,the Inter-University Cooperation Project(Cooperation and Exchange,Collaborative Innovation)in Liaoning Province,and the Liaoning Postgraduate Education and Teaching Reform Project(LNYJG2022291).
文摘The shell surface of Manila clam(Ruditapes philippinarum)has a variety of colors and stripes,with diverse shell color polymorphism.As an important trait of economic shellfish,shell color plays an important role in the selection breeding of shellfish species.In this study,we extracted melanin from the shell and mantle of R.philippinarum by the hydrochloric acid method and measured the melanin content by spectrophotometry.The absorption spectrum of melanin and its absorption peak at 350 nm absorbance was determined.We found significant differences in the melanin content of clams with dark strain and light strain,as well as four different shell colors.Moreover,we further detected the activities of enzymes related to melanin synthesis in R.philippinarum mantle,such as tyrosinase(TYR),tyrosine hydroxylase(TH),dopa decarboxylase(DDC),N-acetyltransferase(NAT),and N-β-alanyldopamine(NBAD)in the mantle of R.philippinarum.The results showed that the activities of TYR,TH,DDC and NAT were positively correlated with the content of melanin.However,the activity of NBAD was negatively correlated with the content of melanin.Altogether,these results indicating that these enzymes are involved in the regulation of the melanogenesis pathway of R.philippinarum.This study provides valuable information for further research on shell color genetic mechanism and breeding of R.philippinarum.
