Impact of three different processing methods on the digestibility and allergenicity of Chinese mitten crab(Eriocheir sinensis)tropomyosin

The tropomyosin(TM)fractions of crab protems may cause allergic reactions in mdividuals susceptible to allergies;however,efficient and safe methods by which to reduce such allergenicity are not currently available.Therefore,in this study,the effects of three different processing methods,i.e.,microwave,ultrasound,and high temperature-pressure(HTP)treatments,on the digestion stability of TM from Chinese mitten crab muscle and the allergenicity of TM digestion products were explored.sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that microwaving had little effect on the digestion stability of TM.In contrast,ultrasound and HTP treatments facilitated the degradation of TM.Similarly,Western blotting and inhibition ELISA indicated that the IgE-binding activity of TM was significantly reduced after treatment with ultrasound or HTP.Among the three different proces sing methods,HTP was the most effective method for improving digestibility of TM and reducing immunoreactivity.This finding provides new insights into treatments for crab allergies.

Microsatellite analysis of genetic diversity and population structure of Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crab （Eriocheir sinensis） has higher commercial value as food source than any other species of Eriocheir in China. To evaluate the germplasm resources and characterize the genetic diversity and population structure of the crabs in different water systems, two stocks and two farming populations were assessed with 25 polymorphic microsallite loci available in public GenBank. Basic statistics showed that the average observed heterozygosity （Ho） amongst populations ranged from 0.5789 to 0.6824. However, a remarkable presence of inbreeding and heterozygote deficiencies were observed. To analyze population structure, pairwise FST coefficients explained only -10.3% variability from the subdivision of mitten crab populations, the remaining variability stems from the subdivision within subpopulations. Although the four populations had slight differentiation, different allelic frequencies resulted in distinct population structures. Two stocks and one farming population were clustered together to the phylogenetic branch of Yangtze crab, with an approximate membership of 95%. Whereas, another farming population was clustered singly to the phylogenetic branch of the Liaohe crab, with a membership of 97.1%. The tests for individual admixture showed that Yangtze crab had probably been contaminated with individuals from other water systems. Genetic relationships between populations also supported the conclusion that Yangtze crab and Liaohe crab had different gene pools in spite of the origins of the same species.

Using Sr isotopes to trace the geographic origins of Chinese mitten crabs

Identifying the geographic origins of Chinese mitten crabs is important for food safety and fair market competition.In this study,we used strontium(Sr) isotopes as a tool to trace the geographic origins of Chinese mitten crabs.Chinese mitten crabs,water,and different types of crab feed were collected from four different lakes for Sr isotope analyses.The results showed that the Sr isotope compositions of the different parts from one single crab were consistent within error,indicating that any piece of a crab could be used to represent the Sr isotope characteristics of the whole crab.The Sr isotope compositions of Chinese mitten crabs from the same lake were consistent within the analytical error,and the values were similar to the Sr isotope composition of the water from the same lake.However,the Sr isotope compositions of water and crabs from different lakes are significantly different.Therefore,the Sr isotope compositions of Chinese mitten crabs are mainly controlled by lake water composition,while the impact of feed is limited.This study provides an effective method for tracing the geographic origins of Chinese mitten crabs.

Identification and Genetic Diversity Analysis of Chinese Mitten Crab(Eriocheir sinensis) in the Liao River Area

Chinese mitten crab （Eriocheir sinensis） is an indigenous and ecologically and economically important species in the Liao River area, but its identification and genetic diversity remain poorly understood. To evaluate the germplasm resources of this species, samples were collected from these locations： four sub-populations from the Liao River area and one population from the Yangtze River area; one primer was used to distinguish between the Liao River and the Yangtze River crabs. Thirteen loci were used for crab genetic diversity analysis, and basic statistics showed that the collecting samples were purebred in the Liao River area. The average observed heterozygosity （H0） of the Liao River population was 0.5931, and the expected heterozygosity （He） was 0.8064. The polymorphism information content （PIC） was 0.7753, which showed that the Liao River population had high genetic diversity. The genetic differentiation index （FST） averaged 0.0342, meaning a low degree of differentiation; cluster analysis indicated that Hujia （HJ）, Xinli （XL） and Chenjia （CJ） sub-populations were allocated to the same cluster, while Baqiangzi （BQZ） sub-population was isolated. In summary, these data demonstrated that the crabs in the Liao River had high genetic diversity, but low genetic differentiation. Thus, the Liao River population had the potential for breeding selection. Furthermore, this study also provided valuable genetic information for the conservation of Chinese mitten crab.

Genetic Differences of Mitten Crabs Based on RFLP Analysis on Mitochondrial Cytochrome Oxidase Subunit I(COI) Gene

The genetic differences of 15 mitten crab populations from 6 river systems in China's Mainland and 1 population from Russia were studied based on RFLP analysis of mitochondrial cytochrome oxidase subunit I （CO I）. The results showed that Tas I-RFLP pattern could be used as a genetic marker to distinguish Eriocheir hepuensis from Eriocheir sinensis, Eriocheirjaponica and Eriocheir leptognathus; genetic distances among 13 populations of Eriocheir sinensis range from 0 to 0.015, indicating that they were different geographic strains; the subspecies status of Eriocheir sinensis and Eriocheir hepuensis （population from Nanliujiang） were considered owning to their genetic distances of 0.02-0.044, indicating that genetic divergence between them was low; Eriocheir leptognathus （population from Nanpaihe, Tianjin） was the most distant taxon with genetic distances value of 0.147-0.195, which could be defined as genetic distances between species in genus Eriocheir.

Water quality, nutrient budget, and pollutant loads in Chinese mitten crab (Eriocheir sinensis) farms around East Taihu Lake

To understand the factors causing frequent outbreaks of harmful algae blooms in the Taihu Lake, China, we studied water quality and nutrient budget in Chinese mitten crab (Eriocheir sinensis) farm ponds in the eastern part of the lake from November 2007 to December 2009. We estimated the nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) loads. Materials input and output ponds, water exchange, and applied management practices of 838.5-hm2 crab ponds were surveyed using questionnaires. Water quality of 12 ponds, which were located no more than 2 km from East Taihu Lake, were monitored. The results show that water quality in the crab ponds was better than reference data. Feeds, including corn seed, commercial feed, trash fish, and gastropod, were the major sources of N and P input in the crab ponds, contributing 88.7% and 94.9%, respectively. In total, 60.5% of N and 37.3% of P were sequestered by macrophytes, and only 15.7% and 8.5% of them were discharged as effluent. The net loads of N and P in effluent were 16.43 kg/hm2/cycle and 2.16 kg/hm2/cycle, respectively, while the COD load was -17.88 kg/hm2/cycle. This indicated that crab farming caused minor negative impact on the trophic status of the lake area, which was attenuated by macrophytes. However, wastewater purification is still necessary in crab faming.

Sustainable fisheries in shallow lakes:an independent empirical test of the Chinese mitten crab yield model

Next to excessive nutrient loading,intensive aquaculture is one of the major anthropogenic impacts threatening lake ecosystems.In China,particularly in the shallow lakes of mid-lower Changjiang(Yangtze) River,continuous overstocking of the Chinese mitten crab(Eriocheir sinensis) could deteriorate water quality and exhaust natural resources.A series of crab yield models and a general optimum-stocking rate model have been established,which seek to benefit both crab culture and the environment.In this research,independent investigations were carried out to evaluate the crab yield models and modify the optimum-stocking model.Low percentage errors(average 47%,median 36%) between observed and calculated crab yields were obtained.Specific values were defined for adult crab body mass(135 g/ind.) and recapture rate(18%and 30%in lakes with submerged macrophyte biomass above and below 1 000 g/m^2)to modify the optimum-stocking model.Analysis based on the modified optimum-stocking model indicated that the actual stocking rates in most lakes were much higher than the calculated optimum-stocking rates.This implies that,for most lakes,the current stocking rates should be greatly reduced to maintain healthy lake ecosystems.

池塘养殖“六月黄”中华绒螯蟹肝胰腺的滋味特征

为揭示“六月黄”中华绒螯蟹食用部分(几乎全部为肝胰腺)的滋味品质特征,利用味觉分析系统,研究昆山市养殖池塘产雌、雄“六月黄”中华绒螯蟹肝胰腺的滋味特征。结果表明,新鲜蒸制的“六月黄”中华绒螯蟹肝胰腺的基本味味觉指标中,鲜味非常突出,其次是苦味和涩味。而其回味味觉指标中苦味回味最高,其次是涩味回味和鲜味回味。“六月黄”雌、雄蟹个体间,苦、涩味和苦味回味等味觉强度指标均有极显著差异(P<0.01)。相关线性判别分析的初始验证判别和交互验证回判的正确率均可达到100%。池塘养殖“六月黄”中华绒螯蟹肝胰腺滋味具有显著性别差异性,雄蟹的滋味特征显示出较雌蟹更为美味的趋势。

基于AlexNet模型的大闸蟹自动分级系统设计与实现

针对目前大闸蟹人工分级方法的局限性,设计基于Matlab图像处理的大闸蟹分级系统。首先,在湖州市太湖养殖基地采集不同等级大闸蟹背部和腹部图像,对采集的图像进行灰度化、阈值分割、形态学等预处理。然后利用卷积神经网络AlexNet模型提取大闸蟹公母特征,利用面积法计算其大小。通过选取的10只大闸蟹的重量和系统计算得到的像素转化为面积参数,分析得到大闸蟹背部图像像素占比与其重量成近似正比例关系,因此可根据背部图像的计算值得到其大小特征。根据大闸蟹公母、大小特征完成分级。实验结果表明,系统在大闸蟹公母识别方面平均准确率达到92.655%,大小分级方面平均准确率达到95%。

中华绒螯蟹“长荡湖1号”选育第二代扣蟹阶段养殖性能研究

为探究中华绒螯蟹(Eriocheir sinensis)“长荡湖1号”A系和B系选育第二代扣蟹的生长性能和养殖效果,在相同养殖条件下,以未选育的养殖群体扣蟹为对照进行了网箱养殖试验。结果表明:(1)大眼至豆蟹阶段,不论是平均体质量、增重倍数还是成活率,“长荡湖1号”B系均显著高于对照组(P<0.05),“长荡湖1号”A系较对照组具有一定的优势,但差异不显著。(2)扣蟹阶段,“长荡湖1号”B系的平均体质量均显著高于对照组(P<0.05),“长荡湖1号”A系9月份体质量与对照组接近,其他月份均显著高于对照组(P<0.05)。就生长速度而言,在6—7月期间,“长荡湖1号”A系和B系的生长速度显著快于对照组(P<0.05)。(3)“长荡湖1号”B系养殖效果最佳,具体表现在养殖产量和成活率最高,显著高于其他两个组,且1龄早熟率和饲料系数最低(P<0.05)。(4)就规格分布而言,“长荡湖1号”A系和B系的体质量在3.00~5.99 g和6.00~8.99 g两个区间内的比例低于对照组,在12.00~14.99 g和≥15.00 g两个区间内显著高于对照组(P<0.05),即A系和B系大规格蟹所占的比例相对更高。综合评价,“长荡湖1号”A系和B系选育第二代在扣蟹阶段成活率高,平均规格大,其余生长性能也优于未经选育的对照组。

An Experimental Study on the Gait Patterns and Kinematics of Chinese Mitten Crabs

Despite the many studies on eight-legged animals and the importance of their mechanics of terrestrial locomotion, the mechanical energy of crabs in voluntary locomotion on uneven, unpredictable terrain surfaces has received little attention thus far. In this paper, motion video images of Chinese mitten crab （Eriocheir sinensis Milne-Edwards） locomotion on five types of terrains were recorded using a high-speed three-dimensional （3D） recording video system. The typical variables of locomotion such as gait patterns, duty factor, mechanical energy of the mass center, mass-specific write of the total mechanical power of the mass center, and percentage recovery, were analyzed. Results show that the Chinese mitten crab uses random gaits instead of the alternating tetrapod gait with the increasing terrain roughness. The duty factors of the rows of the leading legs are greater for all terrains than those of the rows of the trailing legs. On smooth terrain, the duty factors of the rows of the trailing legs are greater than that on rough terrains. Kinematic measurements and calculations reveal that similar to mammals, birds, and arthropods, the Chinese mitten crab uses two fundamental gaits to save mechanical energy： the inverted pendulum gait and the bouncing gait. The bouncing gait is the main pattern of mechanical energy conservation. The low probability of injury and energy expenditure due to adaptations to various terrains induce the Chinese mitten crab to modify the mass-specific rate of the total mechanical power of the mass center. The statistical results of percentage recovery also reveal that the Chinese mitten crab has lower energy recovery efficiency over rough terrains compared with smooth terrains.

Evolutionary relationship of three mitten crabs(Eriocheir sp)revealed by mitogenome and 5S ribosomal DNA analysis

To reveal the evolutionary relationship of three mitten crabs(Eriocheir sinensis,E.hepuensis,and E.japonica),complete mitogenomes and nuclear 5S rDNA sequences were analyzed.Sequencing revealed that the mitogenomes analyzed shared conserved organization of the coding and non-coding regions but genetic variation was identified.Among the three mitten crabs distinct tandem repeats were identified in the mitochondrial D-loop region.The 5S gene(5S rDNA)sequence was highly conserved across the three species,whereas non-transcribed spacer(NTS)region exhibit high levels of variation including insertions,deletions and point mutations.Cluster analysis suggested that the three mitten crabs had their own independent 5S rDNA sequence variation and evolutionary pattern.Both mitogenome and 5S rDNA sequence analysis revealed significant genetic variation across the mitten crabs species.Phylogenetic analysis using mitogenome and 5S rDNA sequences demonstrated that E.japonica was relatively more distant from E.sinensis and E.hepuensis.This study extended our previous knowledge and confirmed that the three mitten crabs are likely to be genetically differentiated species.In addition,our study also provided insights into the conservation of pure natural resources of E.sinensis,an important aquaculture species.

配合饲料糖脂比对中华绒螯蟹生长、体组成和性腺发育的影响

探究配合饲料不同糖脂比替代冰鲜鱼对中华绒螯蟹生长、体组成和性腺发育的影响。在为期6周的饲养试验中,采用5种不同糖脂比(4.09、3.00、1.93、1.40、1.05)的中华绒螯蟹配合饲料(各配合饲料分别命名为:diet 1、diet 2、diet 3、diet 4、diet 5组)替代冰鲜鱼,观察不同糖脂比下的配合饲料对中华绒螯蟹[初始平均体重(98.36±8.17)g]的生长性能、体组成、性腺指数及性腺脂肪酸的营养成分等的影响。结果显示:存活率方面,冰鲜鱼组的中华绒螯蟹成活率(63%)显著低于配合饲料组(P<0.05)。增重率方面,diet 3组(糖脂比1.93)中华绒螯蟹增重率最高[(0.89±0.07)%]。体组成和性腺发育方面,diet 3组(糖脂比1.93)中华绒螯蟹的肝胰腺中总脂肪含量[(21.11±6.14)%]显著低于其他组(P<0.05),性腺中的总脂肪含量[(38.45±6.78)%]显著高于其他组(P<0.05),性腺指数[(14.67±2.35)%]显著高于除diet 4组外的其他组(P<0.05);性腺不饱和脂肪酸含量方面,各处理组中华绒螯蟹性腺中的花生四烯酸、二十碳五烯酸和二十二碳六烯酸等脂肪酸含量存在差异,其中diet 3组(糖脂比1.93)的花生四烯酸含量显著高于其他组、二十碳五烯酸和二十二碳六烯酸含量显著高于除diet 4组以外的其他组(P<0.05)。在中华绒螯蟹初始平均体重为(98.36±8.17)g,饲养6周的试验条件下,相比冰鲜鱼组,配合饲料diet 3组(糖脂比1.93)中华绒螯蟹具有更高的存活率、增重率及性腺指数。配合饲料性腺指数的提高可能与配方中更适宜的糖脂比有关,这为营养物质从肝脏中积累进而转移到性腺中提供了物质基础和能量基础。

水质因子对阳澄湖大闸蟹生态养殖的影响

在昆山市巴城镇武神潭村设立观测试验点,对水温、溶解氧、pH、氨氮及大闸蟹生长动态情况进行监测,讨论适宜大闸蟹生长的水质环境。结果表明,水温对于大闸蟹的影响最大,温度突然变化或者超过30℃易造成大闸蟹的死亡;溶解氧白天呈单峰型,藻类对于溶解氧贡献最大;7月中旬后pH逐步下降且趋于平稳,氨氮总体较低,利于大闸蟹生长。水温28℃左右、溶解氧维持4 mg/L以上、pH 7.5~8.5是阳澄湖大闸蟹适宜生长的水质环境。

浙江地区中华绒螯蟹中甲基汞分布特征与食用风险

为了研究浙江地区中华绒螯蟹中甲基汞的分布特征与食用风险,在浙江主要养殖地区的养殖场设点抽样,利用LC-AFS6000液相色谱原子荧光联用仪检测样品可食部分中的甲基汞含量。结果表明,中华绒螯蟹的蟹肉中甲基汞含量明显高于蟹黄中的甲基汞含量,蟹肉中的甲基汞含量远小于0.5 mg/kg,吴兴乔溇采样点的蟹肉中甲基汞含量最高达到0.043 mg/kg。综上所述,浙江地区中华绒螯蟹符合国家相关要求,可以放心食用,同时建议对甲壳类动物中重金属甲基汞限量作更细的区分和说明。

不同品系中华绒螯蟹群体单性化养殖对生长性能及水质的影响

近年来,中华绒螯蟹单性化养殖技术逐渐受到养殖者的青睐,其不同品系单性化养殖技术对环境影响尚不清晰。本研究通过试验比较了中华绒螯蟹早上市新品系、长江蟹这2类群体在雌雄分养和雌雄混养模式下成蟹规格、成活率、增重率、产量等生长性能、饵料模式、效益情况和养殖尾水情况。结果表明:长江蟹平均产量明显高于早上市新品系,同一品系内雄蟹组的平均产量均最高,早上市新品系的成活率及增重率普遍低于长江蟹,但在两种品系内不同组别表现不同;以冰鲜鱼为主的饵料模式,不同品系中华绒螯蟹均表现雌蟹组饵料系数最低、饵料转化效率最高,且早上市新品系的雌蟹组优于长江蟹雌蟹组;早上市新品系的平均投入低于长江蟹,且以早上市新品系雌蟹组最低,上市时间早晚的差异导致早上市新品系单价比长江蟹高,平均利润也明显高于长江蟹;中华绒螯蟹不同品系、不同养殖模式下,尾水所有指标均达到DB 32/4043—2021的二级标准,总磷、高锰酸盐指数达到一级标准,两种品系高锰酸盐指数趋势一致,雌蟹组养殖池塘高锰酸盐指数较低。

梯形透空丁坝局部水动力特性对底栖动物生境演替的影响机制

针对因梯形透空丁坝局部水动力特性对底栖动物栖息地的影响机制尚不明确,限制了此类结构的大范围推广应用的问题,依托长江深水航道建设的示范应用工程,构建三维水动力数值模型,选择中华绒螯蟹为指示物种,研究了不同径流条件下梯形透空丁坝局部水动力特性及其对指示物种栖息地的影响;结合梯形透空丁坝不同时期沉积物和底栖动物的监测数据,分析了梯形透空丁坝对底栖动物生境演替的影响机制。结果表明:梯形透空丁坝迎流面产生的上升流将主流引导至丁坝后上方,在汛期为中华绒螯蟹提供了避洪场所;坝内及坝后较小的流速和丰富的流场结构为中华绒螯蟹提供了索饵场和越冬场。

高功率脉冲微波处理河蟹肉货架期预测模型的建立

目的探究不同温度贮藏过程中河蟹肉品质变化及货架期预测模型。方法将河蟹肉经过高功率脉冲微波处理后,设置不同温度(4、15、25℃)贮藏,测定河蟹肉在贮藏期间菌落总数(total viable count,TVC)、挥发性盐基氮(total volatile base nitrogen,TVB-N)和硫代巴比妥酸值(thiobarbituric acid reactive substance,TBARS)的变化,并做感官评定。以TVC和TVB-N为指标建立动力学模型,并结合Arrhenius方程构建河蟹肉的货架期预测模型。结果以TVC和TVB-N为指标建立的货架期预测方程分别为t=(lnC_(t)-lnC_(0))/[3.54×10^(7)exp(-46650/RT)]和t=(lnC_(t)-lnC_(0))/[2.03×10^(7)exp(-42750/RT)]。经验证,模型预测值与实测值的相对误差值均在10%以内。结论表明所建立的货架期预测模型能够比较准确地预测河蟹肉在4~25℃贮藏温度范围内的货架期,为实际生产提供理论依据。

蟹肉酶解物的鲜味物质分析及鲜味肽的鉴定

以中华绒螯蟹为研究对象,以水解度和感官评价为评价指标,采用木瓜蛋白酶、胰蛋白酶、复合风味酶、中性蛋白酶、碱性蛋白酶、胃蛋白酶对蟹肉进行酶解,利用氨基酸分析仪和高效液相色谱技术对酶解物中呈味物质进行分析,经分离纯化后采用高效液相色谱串联质谱技术鉴定酶解物中鲜味肽的氨基酸序列。结果表明,中华绒螯蟹蟹肉经胰蛋白酶酶解后,鲜味浓郁、感官评价最佳,其水解度为(51.99±1.85)%,其中鲜味肽、谷氨酸、5’-单磷酸肌苷(5’-inosine monophosphate,5’-IMP)和琥珀酸是主要鲜味物质,经质谱鉴定及鲜味预测筛选,得到14条分子量为795.42~981.55 Da的具有潜在鲜味特性的肽。

发酵棉籽粕替代豆粕对中华绒螯蟹幼蟹生长性能、免疫功能、抗氧化能力和肠道健康的影响

本试验旨在研究发酵棉籽粕替代饲料中不同比例豆粕对中华绒螯蟹幼蟹生长性能、血淋巴生化指标、肝胰腺抗氧化指标、肠道组织结构与菌群的影响。以发酵棉籽粕替代基础饲料中0、20%、40%、60%、80%的豆粕,配制5种等氮等脂的试验饲料,分别命名为FCM0(作为对照)、FCM20、FCM40、FCM60和FCM80,饲喂初始体重为(0.38±0.01)g的中华绒螯蟹幼蟹8周。结果显示:发酵棉籽粕替代不同比例豆粕对幼蟹的成活率、增重率以及特定生长率均无显著影响(P>0.05)。FCM40组肝胰腺指数最高,显著高于FCM0和FCM80组(P<0.05)。发酵棉籽粕替代不同比例豆粕对全蟹水分、粗脂肪和粗蛋白质含量均无显著影响(P>0.05)。FCM60组血淋巴中酸性磷酸酶和碱性磷酸酶活性显著高于其他各组(P<0.05),血淋巴谷丙转氨酶活性显著低于其他各组(P<0.05)。与对照组相比,各替代组(FCM20、FCM40、FCM60和FCM80组)幼蟹肝胰腺还原型谷胱甘肽含量显著升高(P<0.05),FCM60和FCM80组总抗氧化能力(T-AOC)显著升高(P<0.05),FCM80组幼蟹肠道组织结构出现明显损伤。发酵棉籽粕替代40%的豆粕不会对幼蟹肠道菌群α多样性产生显著影响(P>0.05),不会改变肠道主要菌群结构。综上所述,在本试验条件下,发酵棉籽粕替代20%~80%的豆粕对中华绒螯蟹幼蟹的生长性能无显著影响,但以替代比例为20%时生长性能较好;以肝胰腺和肠道健康为评价指标,发酵棉籽粕替代豆粕比例不宜超过40%。