盐度对凡纳滨对虾肌肉中游离氨基酸含量的影响

通过逐渐升高盐度的方法,分别测定盐度为0、10、20、30和40时凡纳滨对虾肌肉中游离氨基酸(FAA)的含量,实验周期40 h。结果表明:在盐度0~40时,总游离氨基酸(TOFAA)、必需氨基酸(EAA)、非必需氨基酸(NEAA)和鲜味氨基酸(TAA)的含量都随盐度的增加而明显升高(P0.05);特别是当盐度从20增加到30时,肌肉中TOFAA、EAA、NEAA和TAA含量的增高幅度最明显。在凡纳滨对虾肌肉FAA中,含量最高的是甘氨酸(Gly),其次是脯氨酸(Pro)、精氨酸(Arg)和丙氨酸(Ala)。在盐度为0~40范围内,肌肉中主要的渗透压调节因子是甘氨酸(Gly)、脯氨酸(Pro)、精氨酸(Arg)、丙氨酸(Ala)和牛磺酸(Tau);而天冬氨酸(Asp)、丝氨酸(Ser)、缬氨酸(Val)、甲硫氨酸(Met)、异亮氨酸(Ile)、亮氨酸(Leu)和酪氨酸(Tyr)的含量在各盐度组未呈现显著变化(P0.05)。在淡水养殖凡纳滨对虾出售前的40 h,通过提高水体盐度来提高凡纳滨对虾肉质的鲜味是完全可行的。     

不同盐度对凡纳滨对虾血淋巴及肌肉游离氨基酸组成的影响

以平均体重为10.50±1.75g的凡纳滨对虾为研究对象,分别在盐度为0、15和30的水体中用同一种饲料喂养20d,探讨不同盐度对凡纳滨对虾肌肉及血淋巴游离氨基酸组成的影响。结果表明,盐度在0、15和30变化时,凡纳滨对虾血淋巴中总游离氨基酸总量随盐度升高而显著增加（P〈0.05）;甘氨酸、谷氨酸、精氨酸和丙氨酸是凡纳滨对虾血淋巴中主要的游离氨基酸成分,其含量随盐度的增加而急剧增加。盐度为0、15和30时,凡纳滨对虾肌肉中游离氨基酸总量随着盐度的增加有增加趋势,但无显著性差异（P〉0.05）。甘氨酸、亮氨酸、苯丙氨酸及精氨酸的含量随盐度由0、15、30的增加而显著增加（P〈0.05）;其他氨基酸在盐度0、15和30增加时,虽无显著性增加（P〉0.05）,但大部分氨基酸有增加趋势。当盐度在0、15和30变化时,游离甘氨酸、谷氨酸、精氨酸和丙氨酸是凡纳滨对虾体内渗透压调节的主要氨基酸。     

不同养殖密度下凡纳滨对虾工厂化养殖排放水研究

为研究不同养殖密度下微生物调控凡纳滨对虾(Litopenaeus vannamei)工厂化养殖排放水的水质状况,设置了3种放养密度(200、400、600尾/m~2),共9口养殖池,跟踪监测了对虾从苗期到养成期不同生长阶段排放水中氨氮、亚硝酸盐氮、硝酸盐氮、硫化物、总磷、COD、重金属等水质指标。结果表明,在3种放苗密度下,当对虾体长8 cm时,排放水的水质基本能达到海水养殖水排放要求的二级标准;当对虾体长≥9 cm时,排放水中无机氮的含量均不符合一级、二级标准。在采用微生物调控的凡纳滨对虾工厂化养殖条件下,放苗密度不超过600尾/m~2时,对虾生长前期养殖水质基本能达到排放要求,生长后期则需要采取一定的养殖废水处理措施,才能达到排放要求。     

生态化池塘养殖模式下凡纳滨对虾与日本囊对虾营养成分的比较

对生态化池塘养殖模式下凡纳滨对虾(Litopenaeus vannamei)与日本囊对虾(Marsupenaeus japonicus)肌肉营养成分与营养品质进行了分析比较。结果表明:该养殖模式下,凡纳滨对虾的水分、粗蛋白、粗脂肪和粗灰分含量与日本囊对虾相近。两种对虾均呈现高蛋白、低脂肪的营养特点;均含有18种氨基酸,呈味氨基酸占氨基酸总量的百分比分别为(29.29±0.16)%、(29.01±0.19)%,必需氨基酸指数(EAAI)分别为68.57、67.90,其构成比例符合FAO/WHO的标准,且凡纳滨对虾的蛋白质营养价值略高于日本囊对虾;两种对虾的水溶性维生素和钙、铁、锌、硒等无机元素含量都十分丰富。综上,生态化池塘养殖的凡纳滨对虾和日本囊对虾肌肉营养价值均非常高,为优质的动物蛋白食品。     

凡纳滨对虾虾头蛋白的内源酶水解研究

试验结果表明,凡纳滨对虾虾头蛋白白内源的最优水解条件为:40℃,pH 6,固液比1∶3,7 h,此时得氨基态氮达6.90 mg/g。从水解液检出16种氨基酸,其中含7种人体必需氨基酸。     

周期性盐度波动对凡纳滨对虾游离氨基酸含量及渗透调节相关基因表达的影响

在实验室条件下,以盐度30为对照组(S0),4 d为1个盐度波动周期,研究了幅度为4(S4)和10(S10)的周期性盐度波动对凡纳滨对虾(Litopenaeus vannamei)稚虾离子通道和水通道相关基因表达、游离氨基酸(FAA)含量及其FAA代谢相关基因表达的影响。结果发现:(1)在盐度波动条件下,凡纳滨对虾离子通道相关基因Na~+/K~+-ATPaseα(NKAα)、Na~+/K~+-ATPaseβ(NKAβ)、碳酸酐酶(CA)、V型H~+-ATPase 1(VHA 1)表达量随盐度波动幅度的增加而极显著升高(P0.01);S4组对虾Na~+/H~+交换因子(NHE)和F型H~+-ATPase 1(FHA 1)表达量显著高于S0和S10组(P0.05);而Cl-通道蛋白(CLC)表达量在各组间差异不显著(P0.05);(2)周期性盐度波动极显著影响凡纳滨对虾水通道蛋白(AQP 4)的基因表达(P0.01),其表达量随盐度波动幅度的升高而下降;(3)周期性盐度波动对凡纳滨对虾肌肉中FAA总量无显著影响(P0.05);鳃中FAA总量随盐度波动幅度的增加而显著升高(P0.05),各组甘氨酸、精氨酸、脯氨酸等含量存在显著差异(P0.05)。(4)与S0组相比,S10组对虾的丙氨酸转氨酶(ALT)表达量极显著升高,S4和S10组对虾的氨基转移酶(AMT)、脯氨酸脱氢酶(PDH)基因表达量极显著降低(P0.01)。实验结果初步表明,周期性盐度波动条件下,凡纳滨对虾渗透调控在转录水平上产生积极响应,且随着盐度波动幅度的增大,对虾的渗透适应性调控水平升高。在盐度波动幅度达到10时,凡纳滨对虾仍能维持体内的渗透平衡,说明其具有较强的耐受盐度波动的能力。     

浓海水条件下凡纳滨对虾血清免疫生理指标比较

为探索利用海水淡化产生的浓海水开展水产养殖的可能性,研究了凡纳滨对虾对浓海水的应激免疫反应.实验用浓海水由盐度30的天然海水添加粗盐配制而成.实验组设盐度40和36两种,对照组为自然海水盐度30.分别检测凡纳滨对虾高盐度应激后0、2、6、12、24、48、96 h时的血清蛋白含量和酸性磷酸酶、超氧化物歧化酶、血清溶菌酶活性、血清凝血时间.结果表明,浓海水对凡纳滨对虾血清蛋白含量、酸性磷酸酶活性和血清凝血时间均有极显著影响（P＜0.01）,但对凡纳滨对虾血清溶菌酶活性、超氧化物歧化酶活性无显著影响（P＞0.05）.     

凡纳滨对虾饲料添加剂的研究进展

凡纳滨对虾(Litopenaeus vannamei)俗称南美白对虾,是目前世界养殖产量最高的三大虾种之一,具有对水环境抗逆能力强、营养要求低、生长速度快,虾体含肉量大、肉质鲜美、营养丰富等诸多优点,自1998年来,在广东、广西、海南等省(区)广为     

凡纳滨对虾养殖成本控制浅析

本文主要从养殖管理、饵料选择投喂及苗种选择等几方面介绍了凡纳滨对虾在养殖过程中成本控制技术要点,为指导生产实践提供借鉴。     

长期高碱胁迫下凡纳滨对虾基因表达差异研究

凡纳滨对虾(Litopenaeus vannamei)具有较强的环境适应能力,对盐碱水环境有一定的耐受性,但在高pH、高碱环境下的存活率不稳定。为探究凡纳滨对虾对长期高碱胁迫的响应机制,本研究以低碱对照组(LSW：碳酸盐碱度为3 mmol/L,盐度为6,pH为8.1)和高碱胁迫组(AW：碳酸盐碱度为10 mmol/L,盐度为6,pH为8.8)养殖42 d的凡纳滨对虾肠道和鳃组织作为实验材料,通过Illumina平台进行转录组测序,对测序数据进行拼接、注释,进而筛选、分析高碱胁迫下的差异表达基因及调控通路并进行定量PCR验证。结果显示,2个组织共同差异表达基因有243个,其中,98个表达上调,145个表达下调。肠道中差异表达基因主要集中在糖代谢、碳水化合物消化吸收、胆汁分泌、ABC跨膜转运、紧密连接以及免疫调节等途径。鳃中差异表达基因主要集中在谷胱甘肽代谢、碳酸氢盐转运、精氨酸合成、糖代谢以及离子转运等相关途径。进一步筛选获得10个最显著的差异表达基因,经qRT-PCR验证发现,凡纳滨对虾鳃中碳酸酐酶(CA1、CA10)、蜕皮激素诱导蛋白(Eip74EF)、β-半乳糖基转移酶(UGT8)基因在高碱胁迫下均表达下调,而Na+/K+-ATPase-α (NKA-α)、Na+/K+ transporting ATPase interacting (NKAIN)、氨转运蛋白(Rhbg)、苹果酸脱氢酶(MDH)等基因表达上调,与转录组表达趋势一致,推测其可能参与了对虾高碱胁迫下的应激响应。凡纳滨对虾表现出较强的高碱适应性,可能是通过下调鳃中CA的表达,补偿体内碱中毒,上调Rh氨转运蛋白防止氨在体内积累,上调NKA相关基因维持体内渗透平衡;但蜕皮激素诱导蛋白(Eip74EF)显著下调,推测其蜕皮功能受到影响。本研究为深入探讨凡纳滨对虾在长期高碱胁迫条件下的生理响应机制提供了基础数据。     

几种牡蛎在保鲜中游离氨基酸和牛磺酸的变化

牡蛎是一种营养丰富的水产动物,曾被誉为“海洋牛奶”［１］。其高营养价值和医疗保健作用,在很大程度上取决于含有较高的风味营养物质。这些物质在细胞内起着调节渗透压的作用,同时也赋予牡蛎所特有的鲜味和营养。据报道［２］,海产动物体内游离氨基酸、牛磺酸等的变化与原有的含量水平、细胞的自溶作用和随之而发生的微生物生长繁殖有紧密关系。８０年代初,日本学者研究鲐、鲣、金枪鱼等在冷藏过程中,从新鲜状态到初期腐败阶段ＦＡＡ含量变化与相关鲜度指标的关系［３．４］ 我国牡蛎主要品种有僧帽牡蛎（Ｏｓｔｒｅａ ｐｌｉａｔｕ…     

贮藏过程中凡纳滨对虾生物胺的变化

以邻苯二甲醛(OPA)为柱后衍生化试剂,采用反相HPLC法测定凡纳滨对虾(Litopenaeus vannamei)中的酪胺(Tyr)、腐胺(Put)、尸胺(Cad)、组胺(His)、胍丁胺(Agm)、精胺(Spe)和亚精胺(Spd)等7种生物胺。结合虾的感官分析、pH值和T-VBN值测定等方法评价凡纳滨对虾的品质,分析了凡纳滨对虾在不同贮藏温度和贮藏时间下的生物胺种类及含量的变化。结果表明,在0和4℃两种贮藏温度下,尸胺和腐胺发生的变化均最显著,可以其作为凡纳滨对虾新鲜程度的参考指标,确定最长贮藏时间分别为8d和6d。     

Dynamics of free amino acids in the hemolymph of Pacific whiteleg shrimp Litopenaeus vannamei exposed to different types of stress

We analyzed the dynamics of amino acids, ammonia-N, and carbohydrates in hemolymph when Pacific whiteleg shrimp Litopenaeus vannamei was subjected to air-exposure and low-salinity stresses. Glycine, l-arginine, and d- and l-alanine levels in hemolymph were increased under both stress conditions. Ammonia-N, a product of amino acid catabolism, also increased in level. These results suggest that the above-mentioned amino acids are used as energy sources. Levels of total carbohydrates, the sum of glucose and other carbohydrates, in the hemolymph showed different dynamics between the two types of stress and were not always high. This suggests that other energy sources, such as amino acids, are important when animals are subjected to stress. It is possible that particular amino acids act as energy sources under various stress conditions.     

Biochemical,physiological, and immunological changes during starvation in juveniles of Litopenaeus vannamei

In an attempt to know how the protein level modulates catabolism and its effects on the immune response, we studied juvenile L. vannamei that had been starved for varying period after being conditioned on diet containing either maintenance or optimal dietary protein levels (DPL). The effect of dietary protein level on nutritional reserves management of shrimp and its relation with immune condition was also addressed. Juvenile shrimp were fed for 21 days on diets containing 5% and 40% dietary protein. Hemolymph metabolites (glucose, cholesterol, protein, acylglycerols, and lactate), hemocyanin, osmoregulatory capacity, digestive gland glycogen and lipids, and immune conditions (hemocytes characterization, phenoloxidase activity, respiratory burst: basal and activated) were evaluated and considered as initial condition. After that time, shrimp were starved for 21 days. During starvation time every 7 days nutritional, physiological and immunological condition were evaluated. A reduction in all physiological and immunological indicators was observed with starvation. The protein level of the conditioning diet had a significant effect on this response; generally, the effect was smaller with shrimp previously fed 40% dietary protein. In this sense the present results demonstrate that shrimp are well adapted to tolerate food deprivation for some time but that this tolerance is closely related to its previous nutritional condition. In the case of shrimp fed 40% DPL, wet weight, nutritional and immune condition was significantly affected after 14 days of starvation. In shrimp previously fed 5% DP, tolerance to starving condition was limited to only a few days (7 days) as a result of low reserves of circulatory and mussel proteins. All these results demonstrate that dietary protein levels can governor the immune condition of shrimp through the management reserves metabolism, indicating that a shrimp with a good nutritional condition can tolerate until 14 days without modifying the evaluated immune responses. In this sense it can be concluded that protein metabolism have a central role for shrimp.     

规格与盐度对凡纳滨对虾肌肉营养成分的影响

分析测定了海水池塘养殖不同规格(8.3、12.5、16.7g.尾-1)凡纳滨对虾(Litopenaeus vannamei)及土池淡水养殖规格12.5g.尾-1凡纳滨对虾肌肉中水分、蛋白质、脂肪、灰分、脂肪酸和氨基酸组成,并进行品质评价。结果显示,海水养殖对虾肌肉的水分、脂肪和虾味氨基酸含量随着对虾规格的增大而减少,蛋白质、灰分、氨基酸、必需氨基酸、半必需氨基酸和鲜味氨基酸总量随着对虾规格的增大而增加;相同规格的凡纳滨对虾中,淡水养殖对虾的含水量、脂肪含量和不饱和脂肪酸含量较高,蛋白质、灰分、鲜味氨基酸总量和虾味氨基酸偏低。综合指标表明,海水养殖凡纳滨对虾的营养价值随着规格的增大而提高;在蛋白质、灰分、鲜味氨基酸和虾味氨基酸含量上,海水养殖对虾高于同一规格的淡水养殖对虾。     

Changes in the intestinal bacterial community during the growth of white shrimp,Litopenaeus vannamei

In this study, we documented the changes in the intestinal bacterial community at four stages in Litopenaeus vannamei: 14 days postlarvae (L14) and 1‐, 2‐ and 3‐month old juveniles (J1, J2, J3), using 454 pyrosequencing techniques. The intestinal bacterial community was dominated by three bacterial phyla, Proteobacteria, Bacteroidetes and Actinobacteria at all stages. However, the relative abundance and bacterial lineages varied at the family level. The intestinal bacterial community of L14 and J1 was similar, with dominant members belonging to the Comamonadaceae of Betaproteobacteria. Conversely, bacterial members affiliated to Flavobacteriaceae of Bacteroidetes were dominant in J2 and Vibrionaceae of Gammaproteobacteria was dominant in J3. The abundance of Microbacteriaceae of Actinobacteria also fluctuated during the four stages. Bacterial members of Flavobacteriaceae and Rhodobacteraceae (Alphaproteobacteria) were present through all growth stages, and likely form the intestinal core microbiome of L. vannamei. However, they varied at the operational taxonomic unit (OTU) level through the growth stages. The intestinal bacterial community of pond‐rearing shrimp included the three main bacterial phyla identified above, and an additional group, Mycoplasmataceae of Mollicutes. Our results demonstrate that the intestinal bacterial community of L. vannamei was highly dynamic during the growth stages. Bacterial members belonging to Commamonadaceae dominated in the earlier growth stage of shrimp, possibly influenced by feeding with Artemia nauplii, but there was a shift to Flavobacteriaceae in the mid and Vibrionaceae in the late growth stages.     

饥饿对凡纳滨对虾仔虾摄食行为和消化酶活力的影响

2004年5月,在中国海洋大学海水养殖教育部重点实验室内营造半精养、精养养殖模式,研究短期饥饿(0(对照组)、1、2、3、4、5、6d)对凡纳滨对虾仔虾摄食行为、摄食率及消化酶的影响。结果表明,两种模式中仔虾的摄食行为和摄食率都随饥饿天数的增加而呈现先上升后下降的趋势;半精养模式中,经饥饿再投喂后仔虾的胃蛋白酶、类胰蛋白酶和淀粉酶活力均随饥饿天数的增加呈现先上升后下降的趋势;精养模式中,胃蛋白酶活力也呈现以上趋势,但类胰蛋白酶和淀粉酶活力则在饥饿初期波动,然后下降。凡纳滨对虾仔虾遭遇饥饿胁迫后,通过提高摄食强度、摄食率及消化酶的分泌量来进行能量补充。但随着饥饿时间的延长,其应对饥饿胁迫的能力下降,各种消化酶活力呈降低趋势。实验表明,在半精养模式中,凡纳滨对虾对饥饿胁迫的承受能力高于精养模式。