Characterization of Wnt genes in Argopecten scallops and their involvement in response to different temperature stresses in“Bohai Red”scallops

As“Bohai Red”scallops were originated from the hybrids between the Peruvian scallop(Argopecten purpuratus)and the bay scallop(Argopecten irradians)northern subspecies(Argopecten irradians irradians).Twelve Wnt members were identified from the two subspecies of bay scallop,and 13 Wnt genes were found in the genome of the Peruvian scallop.Protein structure analyses showed that most Wnt genes poses all 5 conserved motifs except Wnt1,Wnt2,Wnt6,and Wnt9 in the bay scallops and Wnt2 and Wnt9 in the Peruvian scallop.Unexpectedly,Wnt8 gene was present while Wnt3 was absent in both the bay scallops and the Peruvian scallop.Phylogenetic analysis revealed that Wnt3 might have disappeared in the early evolution of mollusks.The expression profile of Wnt genes in the“Bohai Red”exposed to different temperatures was examined by qRT-PCR.Results show that expression of Wnt genes responded differentially to temperature changes.The Wnt genes such as Wnt1,Wnt6,Wnt7,Wnt11,and WntA that responded slowly to low and high temperature stresses may be related to the maintenance of basic homeostasis.Other Wnt genes such as Wnt4,Wnt9,Wnt5,and Wnt2 that responded rapidly to low temperature may play an important role in organismal protection against low temperature stress.And yet some Wnt genes including Wnt10,Wnt16,and Wnt8 that responded quickly to high temperature stress may play key roles in response to high temperature stress.The results provide new insights into the evolution and function of Wnt genes in bivalves and eventually benefit culture of“Bohai Red”scallops.

Fossil Scallops from the Cenozoic Duho Formation of the Pohang Basin,Korea

A great number of fossil scallops were found from the Duho Formation of the Pohang Basin,Korea.Most of the specimens are preserved as slightly altered original carbonate shells,and internal and external molds were also observed in the specimens whose calcareous materials were washed out.In particular, external and internal molds are more frequently observed from the thin and small(less than 1 cm

Yield trait improvement of bay scallops following complete diallel crosses between different scallop stocks

This study describes the complete diaUel hybridization between newly introduced bay scallop stock （W） from Canada and local commercial stock （D） grown under laboratory conditions, in China. Larval survival and growth during all life stages （larvae, spat, and adult） were compared among hybrid （DW, WD） and purebred （DD, WW） populations. Significant heterosis was detected for survival during the larval stage （〉 1% of the mid-parent values）. The mean heterosis （Hm） varied in growth throughout the life span. More than 50% of the Hm values were positive and negative in the DW and WD groups, respectively. The influence of maternal effects and mating types （intrapopulation vs. interpopulation crosses） on growth for all life stages was not consistent. Larval survival did not differ significantly （P〉0.05） with maternal effect or mating type. In the harvest stage, shell length （SL）, shell height （SH）, shell width （SW）, and total weight （TW） were larger in the hybrid compared with the inbred groups. Positive Hm values were observed in SL （1.5%）, SW （5.8%）, and TW （12.3%）, and were more significant in the DW groups （6.1%, 4.5%, 6.8%, and 27.2%）. These results suggest that hybridization between two geographic populations is a good tool for improving bay scallop growth. However, unstable heterosis between the two populations requires further study.

Relationships of growth and mortality to enzymatic activity,and the relative mRNA expression of cultured scallops Patinopecten yessoensis in the Yellow Sea, China

The bottom aquaculture of yesso scallop (Patinopecten yessoensis) has developed rapidly in the north of Yellow Sea, China, but not without accompanying productivity problems. We, therefore, conducted field surveys to investigate factors related to growth and mortality rates of bottom-cultured scallops after release. Specifically, we focused on the effects of total antioxidant capacity (TAOC) and three key enzymes involved in antioxidant and metabolic function:glutamic pyruvic transaminase (GPT), lactic dehydrogenase (LDH), and superoxide dismutase (SOD). Across summer and winter, we also measured the relative mRNA expression of GPT and SOD to understand their seasonal variation in the scallops, along with how such variation correlated to growth and mortality. Results show that bottom cultured scallops experienced mass mortality during the first six months post-release. During winter (December), scallops grew more rapidly and suffered less mortality than in summer (August). The observed lower performance probably resulted from less advantageous environmental factors during the summer seasons, such as high temperature and low dissolved oxygen. These environmental stressors enhance protein consumption while decreasing energetic resources in scallops. Furthermore, scallops in summer exhibited high antioxidant levels that probably competed for energy with process integral to growth and survival. These negative factors combined to elevate mortality rates. In conclusion, we provided evidence suggesting correlations between metabolic/antioxidant activity and growth and mortality of bottom-cultured yesso scallops. These correlations implied us an accurate method to estimate the performance of bottom culture system. Suggestions about innovative aquaculture techniques were also discussed in the study. Our results might provide a possible guideline to the improvement of bottom culture techniques for this commercially valuable seafood species.

The phylogeny of native and exotic scallops cultured in China based on 16S rDNA sequences

Scallops of the Family Pectinidae are a valuable resource in marine industry of the world. Understanding the phylogeny of the family is important for the development of the industry. In this study, partial 16S mitochondrial rDNA genes were obtained from 8 scallop species that are commonly cultured indigenous and transplanted species in China. Phylogenetic relationships of Pectinidae were analyzed based on the 8 sequences and other 5 published ones in GenBank, representing 9 genera of the family. The molecular phylogeny trees were constructed using 3 methods with software PHYLIP. The results showe that total 13 species of scallops clustered in 4 clades. Pecten maximus joins P. jacobaeus then Amusium pleuronectes in cluster, indicating close relationship of genus Amusium with Pecten in evolution. P. yes- soensis is close to Chlamys farreri and C. islandica. No enough material was available to single out genus Patinopecten as an independent monophyletic subfamily. The position of Adamussium colbecki indicates that it is far from genus Pecten but near to genus Chlamys in evolution.

The suitability assessment on site selection for bottom seeding scallop culture based on analytic hierarchy process

Scallop culture is an important way of bottom-seeding marine ranching,which is of great significance to improve the current situation of fishery resources.However,there are some problems in site-selection evaluation of marine ranching,such as imperfect criteria system,complex structure,untargeted criteria quantification,etc.In addition,no site-selection evaluation method of bottom-seeding culture areas for scallops is available.Therefore,we established a hierarchy structure model according to the analytic hierarchy process(AHP)theory,in which social,physical,chemical,and biological environments are used as main criteria,and marine functional zonation,water depth,current,water temperature,salinity,substrate type,water quality,sediment quality,red tide,phytoplankton,and zooplankton are used as sub-criteria,on which a multi-parameter evaluation system is set up.Meanwhile,the dualism method,assignment method,and membership function method were used to quantify sub-criteria,and a quantitative evaluation for the entire criteria was added,including the evaluation and analysis of two types of unsuitable environmental situations.By overall consideration in scallop yield,quality,and marine ranching construction objectives,the weight of the main criteria could be determined.Five grades in the suitability corresponding to the evaluation result were divided,and the Python language was used to create an evaluation system for efficient calculation and intuitive presentation of the evaluation outcome.Eight marine cases were simulated based on existing survey data,and the results prove that the method is feasible for evaluating and analyzing the site selection of bottom-seeding culture areas for scallops under various environmental situations.The proposed evaluation method can be promoted for the site selection of bottom-seeding marine ranching.This study provided theoretical and methodological references for the site selection evaluation of other types of marine ranching.

Production traits and fertility of reciprocal hybrids between Argopecten irradians irradians and A.i.concentricus

The two bay scallop subspecies,Argopecten irradians irradians(NN)and A.i.concentricus(SS),are fast growing and major cultured bivalves in China.However,their relatively small sizes and decreasing production traits caused by long-term inbreeding have been major concerns to the industry in the last two decades.Hybridization between the two bay scallop subspecies may provide a new approach to breed a new variety with superior production traits for the industry.For this end,in this study,we hybridized the two bay scallop subspecies in order to obtain a new strain that incorporates the genes of both subspecies.No significant difference was found in fertilization rate,hatching rate and metamorphosis rate between the purebred and crossbred cohorts(NN♀×SS♂,denoted as NS;SS♀×NN♂,denoted as SN).Both mating strategy(intra-vs.inter-population crosses)and egg origin had significant effects on growth and survival at the larval stage.Heterosis was observed in the crossbred and was more pronounced in older stages.Genetic diversity of the reciprocal hybrids,especially that of SN,was increased compared with the purebred cohorts.Almost all hybrids were completely fertile and able to reproduce by selffertilization or by backcrossing with either parent.Apparently,male sterile individuals whose gonads were fully occupied by the ovary part at mature stage were found in the hybrids for the first time.The hybrids,especially SN,may provide precious germplasm resources for the production of ternary hybrids with the Peruvian scallop,A.purpuratus.

Enhanced Wideband Frequency Estimation via FFT: Leveraging Polynomial Interpolation and Array Indexing

Accurate frequency estimation in a wideband digital receiver using the FFT algorithm encounters challenges, such as spectral leakage resulting from the FFT’s assumption of signal periodicity. High-resolution FFTs pose computational demands, and estimating non-integer multiples of frequency resolution proves exceptionally challenging. This paper introduces two novel methods for enhanced frequency precision: polynomial interpolation and array indexing, comparing their results with super-resolution and scalloping loss. Simulation results demonstrate the effectiveness of the proposed methods in contemporary radar systems, with array indexing providing the best frequency estimation despite utilizing maximum hardware resources. The paper demonstrates a trade-off between accurate frequency estimation and hardware resources when comparing polynomial interpolation and array indexing.

Glutathione S-transferase genes in scallops and their diverse expression patterns after exposure to PST-producing dinoflagellates

The glutathione S-transferases(GSTs)are a superfamily of enzymes that function in cellular protection against toxic substances and oxidative stress.Bivalves could accumulate high concentration of paralytic shellfish toxins(PSTs)from harmful algae.To understand the possible involvement of GSTs in protecting bivalves during PST accumulation and metabolism,the GST genes were systemically analyzed in two cultured scallops,Azumapecten farreri and Mizuhopecten yessoensis,which were reported for PST deposition during harmful algae bloom.A total of 35 and 37 GSTs were identified in A.farreri(AfGSTs)and M.yessoensis(MyGSTs)genome,respectively,and the expansion of the sigma class from the cytosolic subfamily was observed.In both scallop species,sigma class GSTs showed higher expression than other members.The high GSTs expression was detected mainly during/after larvae stages and in the two most toxic organs,hepatopancreas and kidney.After ingesting PST-producing dinoflagellates,all the regulated AfGSTs in the hepatopancrcas were from the sigma class,but with opposite regulation pattern between Alexandrium catenella and A.minutum exposure.In scallop kidneys,where PSTs transformed into higher toxicity,more AfGSTs were regulated than in the hepatopancreas,and most of them were from the sigma class,with similar regulation pattern between A.catenella and A.minutum exposure.In M.yessoensis exposed to A.catenella,MyGST-σ2 was the only up-regulated MyGST in both hepatopancreas and kidney.Our results suggested the possible diverse function of scallop GSTs and the importance of sigma class in the defense against PSTs,which would contribute to the adaptive evolution of scallops in marine environments.

ScanSAR图像舰船目标快速检测方法

提出一种ScanSAR图像舰船目标快速检测方法.该方法通过周期性局部亮度变换技术降低了Scalloping效应对舰船检测的影响,在ScanSAR图像拼接前进行基于OpenMP的改进的双参数CFAR舰船目标检测,不仅避免了拼缝对舰船检测造成的巨大影响,而且极大地缩短了舰船检测的时间,提高了舰船检测的时效性,最后通过图像后处理从拼接后的ScanSAR图像中得到最终的检测结果.对15幅ScanSAR图像进行了实验,结果表明,该方法在提高检测性能的同时,检测的时效性也有明显改善.

ScanSAR的Scalloping辐射误差研究

由于在观测带内采用了多波束扫描的工作模式,使得ScanSAR产生了固有的周期性的scalloping效应,影响了ScanSAR的辐射特性。该文基于ScanSAR工作模式的特点,研究了scalloping产生的机理和性质,定量地分析了scalloping引起的辐射误差以及多普勒中心误差与scalloping的关系,并研究了对scalloping进行校正后的剩余误差问题。

Effect of Fouling in Daya Bay Scallop chlamys nobilis (reeve) Cultivation:Food Competition and Nutrient Release

Biofouling is an important factor that affects bivalve farming industry. Fouling organisms may reduce growth and survival rate of the cultured species. Fouler are often filter feeders, so they are potential competitors for food resource with the cultured species. The present study was conducted to measure the impact of fouling on food uptake and nutrient release in April, 2006 in Daya Bay near Guangzhou, China. Results showed that fouling organisms had significant effect on food uptake and nutrient release. The chlorophyll a uptake rate of fouled scallops was 7.53 / Lh ±1.416 / Lh in April, significantly higher than those of cleaned scallops, Le., 4.23 / Lh±2.744 / Lh. The consumption of total particulate matter by fouled scallops in April was 5.52 / Lh± 0.818 / Lh; the corresponding results for cleaned scallops are 2.49 / Lh ±0.614 / Lh Fouling increased ammonia release significantly. The ammonia release rate of fouled scallops was 33.81/Lh ±7.699 / Lh in April, while cleaned scallops released 2.46 / Lh ±0.511 / Lh ammonia. Phosphate uptake of fouled scallops was 2.01± 0.699 / Lh and cleaned scallops released phosphate 6.01 / Lh ＋ 0.876 / Lh in April. There was not significant difference in nitrate consumption between fouled and cleaned scallops. According to the phytoplankton classification of input and output water samples, fouled scallops filtered more phytoplankton species than cleaned scallops. Therefore, this study showed that fouling contributed much to phytoplankton depletion and concentration increase of ammonia in water.

Genetic diversity and specific markers in four scallop species, Patinopecten yessoensis, Argopecten irradians, Chlamys nobilis and C.farreri

The AFLP （amplified fragrnent length polymorphism）technique was used to analyse the genetic diversity in four scallop species, Patinopecten yessoensis, A rgopecten irradians, Chlamys nobilis and C. farreri. The genetic similarity indexes of these four species are 0.8415, 0.7863, 0.7190 and 0.6731, while Shannon diversity indexes are 43.52, 58.87, 80.16 and 92.83, respectively. As analyzed, the genetic diversities in two native species, i.e., C, farreri and C. nobilis, are higher than those in other two introduced species, A. irradians and P. yessoensis. The results also showed that C. nobilis and C, farreri shared the most common loci. The genetic distance indicated that C. nobilis and C. farreri are closely related. Moreover, out of 510 AFLP markers, 21 specific bands are found to distinguish the four species scallops and these markers may be applied to the specific germplasm characterization and molecular assistant classification in scallops.

不同规格虾夷扇贝捕后耐干露特性比较

为探究商品虾夷扇贝规格与其活品耐藏特性之间的关联,对春季上市虾夷扇贝的规格及质量进行分组,再将各组置于4 ℃下湿布覆盖进行3 d冷却干露贮藏,分别于0、1、2 d和3 d采样进行生化代谢指标分析。试验结果显示,市售春季虾夷扇贝依据壳长大致可分成(105.8±1.5) mm、(98.4± 2.3 ) mm及(90.5±1.7) mm 3个规格组,各规格单贝质量相差20~30 g;(98.4±2.3) mm组扇贝的肥满度及闭壳肌出成率较其他两组高,(90.5±1.7) mm组三磷酸腺苷初始含量最高,表明其捕后胁迫耐力好于较大规格扇贝,(90.5±1.7) mm组扇贝同样表现出更好的耐干露特性,干露3 d 三磷酸腺苷含量和核苷酸能荷均明显优于其他两组;糖原含量各组无明显差异。此外,各组扇贝冷却干露2 d后存活率均为100%,干露至第3 d各组开始出现死亡,其中(90.5±1.7) mm组扇贝耐干露特性最好;各组闭壳肌pH与体腔液pH差异不显著;氨基酸分析结果发现,甘氨酸和精氨酸是扇贝闭壳肌游离氨基酸中含量最丰富的氨基酸,其余游离氨基酸变化趋势不明显;体腔液含氮物中,氨含量较高,其余氨基酸含量均较低并在干露期间无明显变化趋势。

Response of phytoplankton to multispecies mariculture:a case study on the carrying capacity of shellfish in the Sanggou Bay in China

A muhispecies model for shellfish polycuhure in the Sanggou Bay in China used for large-scale long-line cultivation of the Chinese scallop Chlamysfarreri, the Pacific oyster Crassostrea gigas and the kelp Laminaria japonica is presented. The model includes key physical processes which are the transports of matter at the system boundary, and the main biological process that is the primary production and nutrients release from the bottom. By the model, the seasonal fluctuations of phytoplankton biomass and dissolved inorganic nitrogen（DIN） in 1994 are simulated. Furthermore, if the kelp culture scale is kept constant and the Chinese scallop and the Pacific oyster culture scales are adjusted, virtual shellfish farms are funded and responses of phytoplankton to the largescale shellfish culture are simulated. According to these simulated results, the room limitation, and the hypothesis that shellfish will not grow well if the phytoplankton biomass is less than 8.2 mg/m^3 , the expandable multiple of scallop culture k and that of oyster culture y are determined as k = -0.276 5y ＋4.690 5 and 0.133 3k ＋0.006 6y≤0.667 5, where, k （ or y） is equal to 1, the culture scale of scallop （ or oyster） is 8.8 x 109 individuals （or 66 ha, with a density of 59 ind./m^2 ）, and the kelp culture scale is 3 300 ha with a density of 12 ind./m^2.

Removal of biomass tar by steam reforming over calcined scallop shell supported Cu catalysts

In this study, the main purpose is to develop low-cost catalysts with high activity and stability for high quality syngas production via steam reforming of biomass tar in biomass gasification process. The calcined waste scallop shell（CS） supported copper（Cu） catalysts are prepared for steam reforming of biomass tar. The prepared Cu supported on CS catalysts exhibit higher catalytic activity than those on commercial CaO and Al;O;. Characterization results indicate that Cu/CS has a strong interaction between Cu and CaO in CS support, resulting in the formation of calcium copper oxide phase which could stabilize Cu species and provide new active sites for the tar reforming. In addition, the strong basicity of CS support and other inorganic elements contained in CS support could enhance the activity of Cu/CS. The addition of a small amount of Co is found to be able to stabilize the catalytic activity of Cu/CS catalysts,making them reusable after regeneration without any loss of their activities.

Effects of hypoxia on survival,behavior,and metabolism of Zhikong scallop Chlamys farreri Jones et Preston 1904

Hypoxia,a frequent occurring threat in coastal regions,often results in mass mortalities of marine organisms and brings a serious ecological problem.The commercially important Zhikong scallop Chlamys farreri is being under such a threat as the risks of eutrophication and hypoxia have risen in their culture areas.However,little information has been known concerning their tolerance to hypoxia and their strategy for survival.In the present study,a 20-day experiment was conducted to determine the ef fects of hypoxia on the survival,behavior,and metabolism of Zhikong scallop.With the LC_(50)for dissolved oxygen(DO)being estimated as 1.8 mg/L,the survival of Zhikong scallop can be greatly challenged even under the moderate hypoxic condition of around 2.0 mg/L DO.The survival rate ranged from 69%to 59%when DO dropped from 3.0 to 2.0 mg/L,and it was further reduced to 47%at 1.5 mg/L DO.In hypoxic conditions,the scallops became significantly active,which may be explained as escape attempts to avoid hypoxic water.To save energy,Zhikong scallop would depress their respiration.However,when DO dropped from 3.0 to 2.0 mg/L,the oxygen consumption rate hardly changed.The upregulation of lactate dehydrogenase activity and the unrepressed phosphofructokinase activity,which often result in the unbalanced cellular homeostasis and energy budget,may account for the observed increase in the mortality rate of Zhikong scallops.In general,Zhikong scallop is sensitive to hypoxia events,though possible escape attempts,depressed respiration,and oxaloacetate-pathway may increase their survival chance.

EFFECTS OF REDUCED SALINITY ON OXYGEN CONSUMPTION AND AMMONIA-N EXCRETION OF CHLAMYS FARRERI

Effects of reduced salinity on the oxygen consumption rate (OCR) and the ammonia N excretion rate (AER) of scallop Chlamys farreri (3.2 5.9 cm in shell height, 0.147 1.635 g in soft tissue dry weight ) were studied in laboratory from March 21,1997 to April 16, 1997. Under the controlled conditions of reduced salinity from 31.5 to 15.0 and ambient temperature 17℃ and 23℃, the concentrations of dissolved oxygen and ammonia N were determined by the Winkle method and the hypobromite method, respectively. Results showed that with controlled reduced salinity, the mean values of the OCR were 2.17 mg/(g.h) at 17℃, and 2.86 mg/(g.h) at 23℃and that the mean values of the AER were 178.0 μg/(g.h) at 17℃ and 147.0 μg/(g.h) at 23℃. The OCR and the AER decreased with reducing salinity from 31.5 to 15.0 both at 17℃ and 23℃. The effects of reduced salinity on the OCR and the AER of scallop C. farreri could be represented by the allometric equation and the exponential equation, respectively.

POLYCULTURE OF SCALLOP CHLAMYS FARRERI AND KELP LAMINRIA JAPONICA IN SUNGO BAY

Several polyculture models of scallop Chlamys farreri and kelp Laminaria japonica currently employedin Sungo Bay and other parts of northern China are described in this paper. Economic benefits of differ-ent polyculture models are analysed based on the growth rate, culture density and market price. In addi-tion, site selection, critical environmental conditions and polyculture problems are discussed in detail.

Tempo-spatial Variation of Nutrient and Chlorophyll-a Concentrations From Summer to Winter in the Zhangzi Island Area (Northern Yellow Sea)

Nutrient and Chlorophyll-a （Chl-a） concentrations were investigated monthly along three transects extending from a mariculturc area to open waters around the Zhangzi Island area from July to December 2009. The objective of this study is to illus- trate food availability to the bottom-sowed scallop Patinopecten yessoensis under the influences of the Yellow Sea Cold Water Mass （YSCWM）, freshwater input and feedbacks of cultivated scallops. Significant thermal stratification was present in open waters from July to October, and salinity decreased in July and August in surface layers in the mariculture area. Nutrient concentrations increased with depth in both areas in summer, but were similar through water column in November and December. On average, nutrient in- creased from summer to autumn in all components except ammonia. Nutrient concentrations lower than the minimum thresholds for phytoplankton growth were present only in upper layers in summer, but stoichiometric nitrogen limitation existed in the entire inves- tigation period. Column-averaged Chl-a concentration was lower in open waters than in mariculture area in all months. It increased significantly in mariculturc area in August and October, and was less variable in open waters. Our results show that nutrients limita- tion to phytoplankton growth is present mainly in upper layer in association with stratification caused by YSCWM in summer. Freshwater input and upwelling of nutrients accumulated in YSCWM can stimulate phytoplankton production in mariculture area. Farming activities may change stoichiometric nutrient ratios but have less influence on Chl-a concentration.