EST-derived SNP discovery and selective pressure analysis in Pacific white shrimp(Litopenaeus vannamei)

Pacific white shrimp has become a major aquaculture and fishery species worldwide.Although a large scale EST resource has been publicly available since 2008,the data have not yet been widely used for SNP discovery or transcriptome-wide assessment of selective pressure.In this study,a set of 155 411 expressed sequence tags(ESTs) from the NCBI database were computationally analyzed and 17 225 single nucleotide polymorphisms(SNPs) were predicted,including 9 546 transitions,5 124 transversions and 2 481 indels.Among the 7 298 SNP substitutions located in functionally annotated contigs,58.4%(4 262) are non-synonymous SNPs capable of introducing amino acid mutations.Two hundred and fifty nonsynonymous SNPs in genes associated with economic traits have been identified as candidates for markers in selective breeding.Diversity estimates among the synonymous nucleotides were on average 3.49 times greater than those in non-synonymous,suggesting negative selection.Distribution of non-synonymous to synonymous substitutions(Ka/Ks) ratio ranges from 0 to 4.01,(average 0.42,median 0.26),suggesting that the majority of the affected genes are under purifying selection.Enrichment analysis identified multiple gene ontology categories under positive or negative selection.Categories involved in innate immune response and male gamete generation are rich in positively selected genes,which is similar to reports in Drosophila and primates.This work is the first transcriptome-wide assessment of selective pressure in a Penaeid shrimp species.The functionally annotated SNPs provide a valuable resource of potential molecular markers for selective breeding.

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

The aim of the present study is to detect the potential of the base population from diallel crosses of eight introduced strains of the Pacific white shrimp（Litopenaeus vannamei） for improving the yield. Heterosis and heritability were estimated for pond survival at commercial farm conditions for the base population that included 207 full-sib families from a nested mating design by artificial insemination. Among all the hybrids,the heterosis ranged from –11.37%（UA1×UA2） to 20.53%（UA3×SIN） with an average of 0.953%. The results showed that more than half of the hybrids（51.85%） have negative heterosis for survival rate, but most of the hybrids with positive heterosis have high estimates. The high proportion of negative heterosis for survival rate reminders us that the survival trait also should be considered in the crossbreeding program to avoid yield decrease. However, high positive heterosis manifested in most of the hybrids for survival indicates the usefulness of these hybrids for improving the survival to obtain higher yield by crossbreeding in this breeding program. The heritability estimate for pond survival was 0.092±0.043 when genetic groups were included in the pedigree, and it was significantly different from zero（P〈0.05）. The results from this study also indicated that significant improvement for survival is possible through selection in L. vannamei.

Effect of Shrimp(Litopenaeus vannamei) Farming Waste on the Growth, Digestion, Ammonium-Nitrogen Excretion of Sea Cucumber(Stichopus monotuberculatus)

In this study, specific growth rate(SGR), ingestion rate(IR), food conversion ratio(FCR), apparent digestion ratio(ADR) and ammonium-nitrogen excretion were determined for sea cucumber(Stichopus monotuberculatus) reared in plastic containers(70 L; 4 containers each diet treatment). Sea cucumbers were fed with five diets containing different amounts of farming waste from shrimp(Litopenaeus vannamei)(100%, 75%, 50%, 25% and 0) and a formulated compound(20% sea mud and 80% powdered algae). Sea cucumbers grew faster when they were fed with diet D(25% shrimp waste and 75% formulated compound) than those fed with other diets. Although IR value of sea cucumber fed with diet A(shrimp waste) was higher than those fed with other diets, both the lowest SGR and the highest FCR occurred in this diet group. The highest and the lowest ADR occurred in diet E(formulated compound) and diet A group, respectively, and the same to ammonium-nitrogen excretion. The contents of crude protein, crude lipid and total organic matter(TOM) in feces decreased in comparison with corresponding diets. In the feces from different diet treatments, the contents of crude protein and TOM increased gradually as the contents of crude protein and TOM in diets increased, while crude lipid content decreased gradually as the crude lipid content in diets increased.

TAT Improves in vitro Transportation of Fortilin Through Midgut and into Hemocytes of White Shrimp Litopenaeus vannamei

Fortilin is a multifunctional protein implicated in many important cellular processes. Since injection of Pm-fortilin reduces shrimp mortality caused by white spot syndrome virus (WSSV), there is potential application of fortilin in shrimp culture. In the present study, in order to improve trans-membrane transportation efficiency, the protein transduction domain of the transactivator of transcription (TAT) peptide was fused to fortilin. The Pichia pastoris yeast expression system, which is widely accepted in animal feeds, was used for production of recombinant fusion protein. Green fluorescence protein (GFP) was selected as a reporter because of its intrinsic visible fluorescence. The fortilin, TAT and GFP fusion protein were constructed. Their trans-membrane transportation efficiency and effects on immune response of shrimp were analyzed in vitro. Results showed that TAT peptide improved in vitro uptake of fortilin into the hemocytes and midgut of Litopenaeus vannamei. The phenoloxidase (PO) activity of hemocytes incubated with GFP-Fortilin or GFP-Fortilin-TAT was significantly increased compared with that in the control without expressed fortilin. The PO activity of hemocytes incubated with 200 μg mL-1 GFP-Fortilin-TAT was significantly higher than that in the group with the same concentration of GFP-Fortilin. Hemocytes incubated with GFP-Fortilin-TAT at all concentrations showed significantly higher nitric oxide synthase (NOS) activity than those in the control or in the GFP-Fortilin treatment. The present in vitro study indicated that TAT fusion protein improved the immune effect of fortilin.

Optimal content and ratio of lysine to arginine in the diet of Pacific white shrimp, Litopenaeus vannamei

The optimal quantity of dietary lysine (Lys) and arginine (Arg), and the optimal ratio of dietary Lys to Arg for Pacific white shrimp Litopenaeus vannamei were investigated. Coated Lys and Arg were added to a basal diet (37.99% crude protein and 7.28% crude lipid) to provide graded levels of Lys and Arg. The experimental diets contained three Lys levels (2.51%, 2.11%, and 1.70% of total diet), and three Arg levels (1.41%, 1.80%, and 2.21% of total diet) and all combinations of these levels were tested. Pacific white shrimp, with a mean weight of 3.62±0.1 g, were randomly distributed in 36 fiberglass tanks with 30 shrimp per tank and reared on the experimental diets for 50 days. After the feeding trial, the growth performance, survival, feed conversion rate (FCR), body composition and protease and lipase activities in the hepatopancreases of the experimental shrimps were determined. The results show that weight gain (WG), specific growth rate (SGR), FCR, body protein, body Lys and Arg content were significantly affected by dietary Lys and Arg (P<0.05) and improved when dietary Lys and Arg levels were 2.11% 2.51% and 1.80% 2.21%, respectively. Protease and lipase activities in the hepatopancreases of the shrimps appeared higher when dietary Lys and Arg quantities were 2.11% 2.51% and 1.80% 2.21%, although the difference was not statistically significant (P>0.05). Therefore, according to our results, the optimal Lys and Arg quantities in the diet of Pacific white shrimp, L. vannamei, were considered to be 2.11%-2.51% and 1.80%- 2.21%, respectively, and the optimal ratio to be 1:0.88-1:1.05.

Application of Wet Waste from Shrimp(Litopenaeus vannamei) with or Without Sea Mud to Feeding Sea Cucumber(Stichopus monotuberculatus)

In the present study, the applicability of the wet waste collected from shrimp(Litopenaeus vannamei) to the culture of sea cucumber(Stichopus monotuberculatus) was determined. The effects of dietary wet shrimp waste on the survival, specific growth rate(SGR), fecal production rate(FPR), ammonia- and nitrite-nitrogen productions of sea cucumber were studied. The total organic matter(TOM) level in the feces of sea cucumber was compared with that in corresponding feeds. Diet C(50% wet shrimp waste and 50% sea mud mash) made sea cucumber grow faster than other diets. Sea cucumber fed with either diet D(25% wet shrimp waste and 75% sea mud mash) or sole sea mud exhibited negative growth. The average lowest total FPR of sea cucumber occurred in diet A(wet shrimp waste), and there was no significant difference in total FPR between diet C and diet E(sea mud mash)(P > 0.05). The average ammonia-nitrogen production of sea cucumber in different diet treatments decreased gradually with the decrease of crude protein content in different diets. The average highest nitrite-nitrogen production occurred in diet E treatment, and there was no significant difference in nitrite-nitrogen production among diet A, diet B(75% wet shrimp waste and 25% sea mud mash) and diet C treatments(P > 0.05). In each diet treatment, the total organic matter(TOM) level in feces decreased to different extent compared with that in corresponding feeds.

Inheritance of AFLP markers and genetic linkage analysis in two full-sib families of the marine shrimp Litopenaeus vannamei(Crustacea,Decapoda)

The cultivation of the marine species of shrimp Litopenaeus vannamei has emerged as one of the segments that best develop in the Brazilian aquaculture, representing the agribusiness that grew the most in recent years. Regarding the economic importance of the farming of this species in Brazil, further studies on genetic improvement were conducted. A F2 segregating population consisting of 192 samples for each G1 and G2 families, from crossing inbred lines was used for the studies performed in the present work. The genetic linkage analysis was based on polymorphic markers derived from nine AFLP (Amplified Fragment Length Polymorphism) primers. Fourteen genetic linkage groups including 103 segregating polymorphic markers were constructed covering350 cMfor G1 and four genetic linkage groups including 59 markers were constructed covering300 cMfor G2. Simple marker analyses were performed among individuals evaluated phenotypically, finding markers linked to genes that may be potentially important and useful to assess characteristics of economic importance for traits related to weight and the disease IMN (idiopathic muscle necrosis). The statistical model including markers explained major proportion of phenotypic characteristic weight in relation to disease incidence IMN.

凡纳滨对虾(Litopenaeus vannamei)不同世代养殖群体的遗传多样性分析

采用微卫星位点对凡纳滨对虾的海南群体(进口亲虾繁育的第1世代:G1)、山东和饶平群体(G2)、湛江2和湛江3群体(G3)、湛江1和上海群体(G4)共4个世代7个养殖群体的遗传多样性进行了分析。从21对微卫星引物中筛选出12对有效扩增引物,对7个群体共280个个体进行扩增,得到10个多态位点,共获得等位基因数63个。各位点的等位基因数在2—15个之间,各群体的平均等位基因数在4.70—5.80之间。平均观测(期望)杂合度在0.36—0.43(0.53—0.65)之间。杂合子偏离指数(D)为负值,表明存在杂合子缺失现象。对7个群体、10个多态位点进行Hardy-Weinberng平衡检测,共有54个偏离平衡。对7个群体间的遗传分化水平进行检测,得到近交系数FIS在9个多态位点均为正值,两两群体间的固定指数FST值在0.149—0.375之间。FST显著性检验表明,各群体之间的遗传分化极显著(P<0.01)。分子方差分析结果显示,大部分遗传变异(72.17%)来自于群体内,来自于群体间的遗传变异(27.83%)较小。凡纳滨对虾不同世代间遗传变异大,随着繁育世代的增加,遗传多样性降低。

凡纳滨对虾(Litopenaeus vannamei)感染白斑症病毒(WSSV)后大颗粒血细胞的变化

采用抗凡纳滨对虾大颗粒细胞的单克隆抗体,应用免疫细胞化学方法,分析了凡纳滨对虾人工感染白斑症病毒(WSSV)后血细胞中大颗粒细胞的变化。研究表明,凡纳滨对虾感染WSSV后,大颗粒细胞的细胞质较正常细胞的多;从WSSV感染凡纳滨对虾的第1天至第3天,大颗粒细胞的数量增加幅度较大。同时,大颗粒细胞占血细胞总数的比例也增加较大第1天为15.2%,第2天为18%,第3天增大到45.9%,而后大颗粒细胞的比例稍有下降,到第8天下降到43.3%,但仍明显高于对照组(健康虾的大颗粒细胞比例为15.2%)。

凡纳滨对虾(Litopenaeus vannamei)池塘生物膜低碳养殖技术研究

采用水体中设置生物膜净水栅对比实验的方法,在6口土池开展生物膜原位修复技术对土池半咸水养殖凡纳滨对虾的节能减排、养殖效益及机理的研究。结果表明,在135d的养殖期间,处理组水质的pH、TAN、NO2-N、无机氮和无机磷浓度分别显著低于对照组7.5%、78.8%、76.2%、53.2%和66.1%(P<0.05),DO浓度极显著高于对照组13.5%(P<0.01);弧菌数极显著低于对照组66%(P<0.01),细菌总数、硅藻相对密度、藻类生物多样性指数分别极显著高于对照组206%、173%、25.6%(P<0.01),藻类密度、蓝藻相对密度分别显著低于对照组64.7%、70%(P<0.05);生物膜上的细菌总数高达5.8×109 CFU/g,而弧菌数为零;虾养殖成活率、虾起捕规格、虾产量分别极显著高于对照组62.5%、53.9%、150%(P<0.01),饲料系数极显著低于对照组26.8%(P<0.01),处理组每公顷池塘养虾增加利润约22.1万元。池塘生物膜低碳养殖技术具有成本低、节能减排、增产增收、操作简便与易推广等优点,具有广阔的应用前景。

Effects of dietary supplementation with tropical microfungi Mucor circinelloides and Trichoderma harzianum powder on growth performance,bacterial communities,and the biomass nutritional profile of white shrimp grow-out culture(Litopenaeus vannamei)

Microfungi have been explored further as supplement constituents in shrimp culture due to their rich protein,lipid,essential amino acids,fatty acids,and various bioactive compounds.The researchers have evaluated the effects of two microfungi powders(Mucor circinelloides and Trichoderma harzianum)as feed supplements on growth performance,bacterial communities,and the biomass nutritional profile of white shrimp(Litopenaeus vannamei).The results showed that commercial/artificial feed(Feng-Li)with supplementation microfungi powder had a different effect on white shrimp growth performance than control after 62 days of the grow-out period.Supplementation with 1.5%M.circinelloides powder(M-2)could improve the growth performance of white shrimp,especially the survival rate(81.33%),final body weight(5.21 g),and shrimp biomass(211.35 g).In contrast,supplementation with 1.5%T.harzianum powder(T-2)did not improve the growth performance of white shrimp compared to control(p>0.05).Furthermore,it also affected the profile of the bacterial community in culture water as well as in shrimp intestines.Supplementation with both microfungi could reduce the total number of bacteria in culture water at the end of the experiment,where the lowest number was obtained in treatment T-2(3.9×10^(5)CFU/mL),followed by M-2(9.9×10^(5)CFU/mL)and control(4.4×10^(6)CFU/mL).In the culture water,20 isolates of culturable bacteria were found during the trial,with the dominant bacteria in M-2:Bacillus cereus,Bacillus velezensis,Gordonia polyisoprenivorans,T-2:Acinetobacter sp.,Gordonia polyisoprenivorans,Micrococcus luteus.Based on average well colour development(AWCD),the highest bacterial activity was in the M-2(0.297-0.707),followed by T-2(0.226-0.717)and control(0.094-0.694).The highest substrate group utilised in M-2 and T-2 were polymers(0.896 and 1.348)and control:amines(0.100).The highest Shannon diversity index was obtained in the M-2(2.508),followed by control(2.286)and the T-2(2.157).As many as 11 isolates of culturable bacteria were found in the shrimp intestine,with dominant bacteria in M-2:Bacillus velezensis,Micrococcus luteus,Bacillus cereus,T-2:Bacillus velezensis,Micrococcus sp.2,Demequina activiva.The highest bacterial activity was in M-2(2.259),followed by control(2.020)and T-2(0.050).The highest substrate group utilisation was in M-2:polymers(2.564),T-2:carbohydrates(0.094),and control:polymers(2.185).The highest Shannon diversity index was in the M-2(3.234),followed by control(3.230)and the T-2(0.751).In addition,1.5%M.circinelloides and T.harzianum supplementation increased white shrimp muscle protein content up to 79.21%and 80.40%,respectively,compared to control(76.73%).In conclusion,using Mucor circinelloides powder as a feed supplement can improve the growth performance of white shrimp,increase the functional/probiotic bacteria:B.cereus and B.velezensis in cultur and shrimp’s intestine,and increase the protein content in shrimp muscle tissue.However,more in-depth research is needed,especially on anti-nutritional compounds from fungi that affect shrimp growth.

透明质酸对南美白对虾虾糜理化性质和凝胶特性的影响

以南美白对虾(Litopenaeus vannamei)虾糜为研究对象,考察不同添加量(0.1%、0.3%、0.5%、0.8%和1.0%,以虾肉的质量计)透明质酸(hyaluronic acid,HA)对虾糜凝胶特性和理化性质的影响。结果显示,一定量HA能够改善虾糜凝胶的质构特性和凝胶强度,提高虾糜凝胶的亮度和白度。适量添加HA还能够促使虾糜凝胶内部自由水和不易流动水向结合水转变,改善虾糜凝胶的水结合特性,提高持水性(water-holding capacity,WHC)。流变学分析表明,一定量HA能使虾糜的储能模量提高,然而低添加量HA会对表观黏度产生不利影响。化学作用力分析表明,离子键和氢键随HA的添加分别呈现先减后增和先增后减的变化趋势,适量HA可以改善疏水相互作用,巯基氧化形成二硫键的过程则被HA抑制。HA还能与虾糜蛋白相互作用,抑制蛋白多聚体的形成,改变蛋白质的构象,促使蛋白质二级结构从α-螺旋向β结构和无规卷曲转变。添加适量HA对虾糜凝胶微观结构同样有所改善,促使虾糜凝胶形成更加均匀致密的微观结构。其中,添加0.8%HA虾糜凝胶具有最高的硬度、咀嚼性、胶着性、凝胶强度以及储能模量和最致密的微观结构,WHC较对照组也显著提高(P<0.05)。而添加0.1%HA虾糜凝胶的质构特性、凝胶强度、WHC、储能模量均较对照组有所降低,微观结构也较为松散。

高压静电场解冻对凡纳滨对虾肌球蛋白结构特征的影响

该研究以去头凡纳滨对虾为材料,以羰基与总巯基含量、表面疏水性与粒径大小、内源荧光光谱与傅里叶变换红外光谱和聚丙烯酰胺凝胶电泳的特征等作为考察指标,以自然解冻(nature thawing,NT)作为对照,研究了高压静电场解冻(high voltage electrostatic field thawing,HVEFT)的场强(1.8、3.8、4.3 kV)和温度(5、15、25℃)对去头虾肌球蛋白结构的影响。结果表明,当场强为3.8 kV时,随着温度的升高,总巯基、粒径、α-螺旋的含量呈先增后减的趋势,表面疏水性呈先下降后上升的趋势,羰基和内源荧光强度逐渐增加。当温度在15℃时,随着场强的增加,总巯基、α-螺旋表现为先增后减的趋势,羰基逐渐增加,表面疏水性则呈现出先下降后上升的趋势。综上所述,当场强为3.8 kV,温度为15℃时,高压静电场解冻对去头肌球蛋白结构影响最小。在此条件下,与NT处理组相比,HVEFT处理组样品的总巯基(3.35 mol/104g)和α-螺旋的占比(30.7%)分别是NT的1.15倍和1.17倍,表面疏水性是NT(22.54μg/mL)的0.42倍。结果表明,HVEFT能较好地维持虾肌球蛋白结构稳定性,有利于去头虾解冻后品质的保持。研究结果为高压静电场技术在水产制品解冻中的应用提供科学依据。

常压浸渍与脉冲真空浸渍麻辣凤尾虾的风味特性及其风味成分分析

为了研究常压浸渍和脉冲真空浸渍调味技术对麻辣凤尾虾风味特性与风味成分的影响,采用HPLC、原子吸收分光光度法、GC-MS等分析麻辣凤尾虾的羟基-α-山椒素、辣椒素、无机盐离子、呈味核苷酸、游离氨基酸及挥发性风味成分,采用偏最小二乘回归(partial least squares regression,PLSR)对其感官特性与主要风味成分进行相关性分析。结果表明,脉冲真空浸渍麻辣凤尾虾的羟基-α-山椒素含量(146.59μg/mg)显著高于常压浸渍的麻辣凤尾虾的含量(129.29μg/mg)(P<0.05),但常压浸渍的凤尾虾中呈味核苷酸与鲜味氨基酸的鲜味叠加效应更好;GC-MS分析显示,麻辣凤尾虾中共检出72种挥发性化合物,其中含16种香气活性化合物。与常压浸渍处理相比,脉冲真空浸渍处理的挥发性成分和香气活性化合物种类更丰富。常压浸渍调味组有4种(芳樟醇、D-柠檬烯、草蒿脑、月桂烯),脉冲真空浸渍组有7种(芳樟醇、D-柠檬烯、草蒿脑、乙酸芳樟酯、2-酰基-噻唑、β-月桂烯、(Z)-3,7-二甲基-1,3,6-十八烷三烯)。感官特性与主要风味成分PLSR相关分析结果与其风味成分含量一致,脉冲真空浸渍调味组花椒味、辣椒味与香气活性化合物相关性较好,常压浸渍调味组鲜味、甜味与Glu、Ala、IMP相关性较好。研究结果为脉冲真空浸渍技术在水产预制食品品调味上的应用提供了理论基础。

上海地区凡纳滨对虾工厂化养殖的发展瓶颈及建议

工厂化循环水养殖具有节约水土资源、养殖密度高、生产控制能力强、自动化程度高以及生态绿色环保等优点,是现阶段我国养殖产业主推的绿色养殖模式之一。文章对凡纳滨对虾工厂化养殖模式的内涵、国内外发展历程和水平等进行了概述,通过调研分析上海实施工厂化养虾的典型案例,发现目前上海地区工厂化养虾存在前期投资较大、运营成本较高、技术支撑体系不够完备、技术和管理类复合型人才缺乏、市场不稳定等瓶颈问题,并提出了加大政府扶持力度、加强基础应用研究、开展技术培训指导、重视品牌战略建设等切实可行的对策和建议,可为上海工厂化养虾的进一步发展和推广提供参考。

纳米银在南美白对虾养殖中的应用研究

研究了纳米银对南美白对虾苗的毒性、弧菌的杀灭能力和抑制效果,以及可能导致养殖水体和养殖对虾中的银累积。结果表明,纳米银对南美白对虾苗的96 h半致死浓度(LC50)为推荐使用浓度(0.5 mL/m^(3))的2241.54倍(1120.77 mL/m^(3)),48 h LC50-为推荐使用浓度的5421.70倍(2780.15 mL/m^(3))。相应的安全浓度(SC)(按0.05的应用系数)分别为96 h SC 56.04 mL/m^(3)和48 h SC 135.54 mL/m^(3)。指出,纳米银能够明显杀灭和抑制养殖水体和对虾身体的弧菌,是一种高效的疾病预防药物,但会造成养殖水体银浓度增加,并在对虾体内有一定量的累积。

一株虾源假交替单胞菌(Pseudoalteromonas sp.)的分离鉴定及口服后对对虾体内弧菌的影响

为探讨对虾细菌性病原的微生物防控技术,采用牛津杯打孔法对分离自对虾育苗池的一株编号为2021041402-14的细菌(简称“02HN”)进行了抗菌测试,分析其对欧文氏弧菌(Vibrio owensii)、哈维氏弧菌(V.harveyi)、坎贝氏弧菌(V.campbellii)、溶藻弧菌(V.alginolyticus)、副溶血弧菌(V.parahaemolyticus)和美人鱼发光杆菌(Photobacterium damselae)等6株虾病原菌的抑菌效果及最低抑菌浓度,通过浸泡感染测试了菌株02HN对凡纳滨对虾(Litopenaeus vannamei)的生物毒性,采用16S rRNA、gyrB-rpoD串联基因序列比对法及生理生化方法对该菌进行了鉴定,并将该菌添加到饲料中投喂对虾,评价该菌对对虾体内弧菌数量的影响。结果表明:菌株02HN对欧文氏弧菌、哈维氏弧菌、坎贝氏弧菌、溶藻弧菌、副溶血弧菌和美人鱼发光杆菌均具有抑菌效果,其最低抑菌浓度分别为2.32×10~4、2.32×10~3、2.32×10~6、2.32×10~6、2.32×10~3、2.32×10~6 CFU/mL;采用02HN浓度为1×10~7 CFU/mL以下的菌液浸泡凡纳滨对虾,生物毒性不明显;分子鉴定显示,该菌与杀鱼假交替单胞菌(Pseudoalteromonas piscicida)及金丽假交替单胞菌(P.flavipulchra)最为接近,为一株假交替单胞菌(Pseudoalteromonas sp.);对虾摄食菌含量分别为1×10~5、1×10~7cells/g的饵料后,其存活及生长无显著性变化,但能显著降低对虾肝胰腺中的弧菌数量(P<0.05)。研究表明,菌株02HN在对虾养殖中具有开发应用潜能,本研究结果可为对虾细菌性病原的生物防控提供生物材料及技术思路。

苏北地区凡纳滨对虾3种主要病毒的分离及快速鉴定

从连云港和盐城等地收集了来自不同对虾养殖池塘的587个凡纳滨对虾(Litopenaeus vannamei)样本,采用基因芯片快速检测技术对样本白斑综合症病毒(white spot syndrome virus,WSSV)、传染性皮下及造血组织坏死病毒(infectious hypodermal and hematopoietic necrosis virus,IHHNV)和虾血虹彩病毒(shrimp henocyte iridescent virus,SHIV)等3种病原体进行分离与快速鉴定。共检测出18个阳性样本,其中13个样本WSSV呈阳性,4个样本IHHNV呈阳性,1个样本SHIV呈阳性;阳性样本占样本总数的3.07%,且阳性样本中WSSV又占了阳性样本总数的72.22%。对这些病原的快速鉴定,可为病害诊断、预警预报、科学防控等提供依据,从而减少暴发性病毒病给对虾养殖带来的经济损失。

高密度CO_2诱导制备虾糜凝胶的特性

为了探索高密度CO2诱导制备蛋白凝胶的可行性,以南美白对虾虾糜为材料,以常压热诱导凝胶为对照,研究压力5～30MPa、时间10～50min、温度50～70℃等因素对虾糜凝胶特性以及基本营养成分的影响。结果表明,高密度CO2处理能够使虾糜形成凝胶,压力、时间和温度对虾糜凝胶特性均有显著影响,在20MPa、60℃、30min和25MPa、60℃、30min条件下制备的虾糜凝胶品质相对较好;与热诱导凝胶相比,高密度CO2诱导的虾糜凝胶强度更大,同时也显著增加了虾糜凝胶的持水能力,减少了营养物质的流失。研究结果表明,高密度CO2具有促进凝胶形成和改善凝胶特性的作用,可以成为替代热处理成为蛋白凝胶制品生产的新技术。

加热方式对凡纳滨对虾滋味成分的影响

以凡纳滨对虾为原料,通过仪器分析法对微波加热与水煮处理的对虾的游离氨基酸、呈味核苷酸、有机酸、甜菜碱和无机离子这些主要滋味成分进行了分析。结果表明:凡纳滨对虾经微波加热与水煮处理后,游离氨基酸总量均有减少,分别下降了15.81%,20.19%;呈味核苷酸总量也均有减少,分别降低了25.07%,25.89%,其中含量最高的腺苷酸(AMP)有所提高,分别增加了4.01%,5.95%;乳酸含量大幅降低,分别减少了53.64%,77.24%;甜菜碱的含量也有明显的差异,分别减少了7.26%,8.83%;呈味无机离子含量差异明显,且微波虾的要高于水煮虾。通过研究分析发现,微波虾中除AMP含量略低于水煮虾外,游离氨基酸、有机酸、甜菜碱和无机离子的含量均高于水煮虾,表明微波虾的滋味优于水煮虾。