响应面优化酶法提取牡蛎糖原工艺条件研究

为研究制备牡蛎(Crassostrea angulata)糖原的最佳工艺条件,通过比较分析了碱性蛋白酶、木瓜蛋白酶、胃蛋白酶、中性蛋白酶和胰蛋白酶等5种不同蛋白酶对牡蛎进行酶解提取糖原的效果,以碱性蛋白酶为最优酶制剂。在对碱性蛋白酶酶解工艺条件进行单因素实验的基础上,应用Box-Bhenken中心组合设计3因素3水平试验方案,通过响应面分析,建立数学模型优化牡蛎糖原的提取条件,以p H、酶解温度和加酶量为自变量,牡蛎糖原提取率为指标,获得碱性蛋白酶水解牡蛎提取糖原的最佳工艺条件,即加酶量4%、p H9、水解温度50℃,此时牡蛎糖原的提取率可达(48.55±0.01)%。试验结果表明,响应面法对牡蛎糖原提取条件的优化方案合理可行,该研究为牡蛎糖原的开发利用提供了理论依据。     

不同育性三倍体长牡蛎性腺发育过程中的营养成分比较

为阐明不同育性三倍体长牡蛎性腺发育与营养成分变化的关系,实验对不育型和可育型三倍体长牡蛎性腺发育过程中的主要营养成分(糖原、总蛋白质和总脂肪含量)进行分析,并与二倍体长牡蛎进行比较。结果显示,三倍体长牡蛎性腺—内脏团、闭壳肌和外套膜3种组织中的糖原含量均显著高于同时期的二倍体长牡蛎,性腺—内脏团和闭壳肌中的总蛋白质含量则显著低于同时期的二倍体。随着性腺发育,可育型三倍体长牡蛎性腺—内脏团的糖原含量下降了31.88%,二倍体长牡蛎下降82.41%,而不可育型三倍体长牡蛎糖原含量下降了0.55%,这与糖原为配子发生供能密切相关。此外,不育型三倍体长牡蛎性腺—内脏团的糖原、总蛋白质和总脂肪含量在繁殖季节中均没有发现明显的波动,而可育型三倍体长牡蛎由于性腺一定程度的发育,其营养成分含量的变化趋势与二倍体类似。研究表明不育型和可育型三倍体长牡蛎在繁殖季节营养成分存在明显的差异,不育型三倍体的糖原品质性状优于可育型,这为长牡蛎育性控制育种提供了重要参考依据。     

牡蛎清洗试验研究与清洗设备设计

分别采用毛刷、高压水、超声波对牡蛎进行清洗,以去除杂质比重为主要指标,探讨几种方式对牡蛎清洗效果的影响,初步确定最佳清洗参数。结果表明:毛刷、高压水、超声波都能够对牡蛎进行有效清洗。模拟人工冲刷式实验最佳工艺条件为:滚刷转速20 r/min,高压水压力8 MPa,流量15 L/min,时间2~5 min;超声波清洗实验最佳工艺条件为:低频(26 KHz),处理时间5 min。此系列工艺条件下牡蛎无死亡,生态冰温保活9 d后,存活率达到95%以上。以试验参数为基础,设计一种集三种清洗方式为一体的组合式牡蛎清洗设备。     

长牡蛎糖原磷酸化酶基因SNPs与生长性状和糖原含量的相关性分析

为研究糖原磷酸化酶基因多态性与长牡蛎(Crassostrea gigas)生长和糖原含量的相关性,本研究对长牡蛎糖原磷酸化酶基因(Cg-GPH)编码区单核苷酸多态性(SNPs)与来自5个家系322个长牡蛎个体的生长性状(包括壳高、壳长、壳宽、总体质量以及软体部质量)和糖原含量进行了关联分析.结果表明,在1940 bp的长牡蛎糖原磷酸化酶基因中共检测到82个SNPs位点,其中63个SNPs位点位于外显子区域,1个SNPs位点位于5′-UTR区,18个SNPs位点位于3′-UTR区,编码区SNPs平均密度为1/25 bp;5个SNPs位点与生长性状存在显著相关(P<0.05),未检测到与糖原含量相关SNPs.根据以上5个SNPs位点共构建得到6个SNP单倍型,其中,Cg-GPH基因的H6(CTGAT)单倍型在总体质量性状方面均显著高于其他5种单倍型(P<0.05),表明H6单倍型可能是对长牡蛎体质量增加最有利的单倍型.研究结果为今后长牡蛎生长性状的遗传改良提供了基础资料.     

改性牡蛎壳粉的制备及其对Cd~(2+)的吸附

以十二烷基磺酸钠(SDS)为改性剂,制备了有机改性牡蛎壳粉,并以Cd2+的去除率为指标进行正交实验分析,确定最佳改性工艺。通过红外光谱(FTIR)、扫描电镜(SEM)、能谱(EDS)对有机牡蛎壳粉进行表征,并进行了其对Cd2+的吸附动力学研究。正交实验结果表明,最佳改性工艺条件为:SDS用量为牡蛎壳粉质量的15%,改性时间为120 min,改性温度为60℃,改性p H值为7。FTIR、SEM和EDS图谱表明SDS对牡蛎壳粉的改性是成功的。动力学研究表明改性牡蛎壳粉对Cd2+的吸附符合准二级动力学方程。     

5种壳色长牡蛎不同组织常规营养成分分析与评价

对壳黑、壳紫、壳橙、壳金和壳白5种壳色长牡蛎(Crassostrea gigas)不同组织包括闭壳肌、外套膜、鳃、性腺-内脏团的营养成分(水分、总蛋白质、总脂肪、糖原、灰分)进行检测分析,比较它们与普通养殖群体营养成分的差异以及5种壳色长牡蛎各组织间营养成分的差异。结果表明,在闭壳肌中,壳紫长牡蛎的总脂肪含量显著高于壳橙长牡蛎(P0.05),其他组分在6个群体中未表现出显著性差异(P0.05);在外套膜中,壳金长牡蛎总脂肪含量显著高于壳黑、壳橙和普通养殖群体(P0.05),壳白长牡蛎的灰分含量显著高于普通养殖群体(P0.05),其他组分在各群体之间未表现出显著性差异(P0.05);在鳃中,长牡蛎壳橙、壳紫、壳白选育群体的糖原含量显著低于对照组(P0.05),其他组分在6个群体之间没有显著性差异(P0.05)。长牡蛎5种壳色选育群体和普通养殖群体的性腺-内脏团在水分、总蛋白质、总脂肪、糖原和灰分中均无显著性差异(P0.05)。4个组织中水分和灰分均以外套膜和鳃中含量最高,闭壳肌中总蛋白质的含量则在4个组织中居首位,总脂肪和糖原含量均以性腺-内脏团中最高。研究结果表明不同壳色长牡蛎之间以及不同壳色与普通对照群体之间在一些重要营养成分上已表现出分化,这为长牡蛎壳色品系选育提供了重要的参考资料。     

近江牡蛎冻干组织糖原含量近红外模型的建立

糖原直接影响牡蛎的风味和营养品质,常作为评价牡蛎品质质量的重要标准。近红外光谱(NIR)模型可以实现糖原含量的快速准确检测。本研究以近江牡蛎(Crassostrea ariakensis)为研究对象,采用微量蒽酮法、近红外技术分别获取了外套膜、鳃、闭壳肌、肝胰腺、唇瓣、性腺等6个组织及全软体部混样共909份样品的糖原含量及光谱数据,结合最小二乘法建立了近江牡蛎6个组织及全软体部的糖原含量预测模型,并对该模型进行了外部验证和交叉验证。结果显示,所测样品光谱数据经一阶求导、乘法散射校正及平滑预处理后,建立的模型最优;所建立的7个模型的建模相关系数(RC)为0.971 6~0.996 3,其外部验证相关系数(REV)及交叉验证相关系数(RCV)分别为0.949 0~0.990 8和0.969 4~0.996 9,且模型交叉验证和外部验证的RPD值均大于2.5,表明所建立的模型能准确预测近江牡蛎相应组织样品的糖原含量。本研究建立的近江牡蛎糖原含量NIR分析模型,不仅丰富了牡蛎糖原含量检测方法的研究资料,还为实现近江牡蛎糖原成分的快速、准确测定提供了技术支撑,在近江牡蛎品质性状改良等领域具有重要的应用价值。     

不同育性长牡蛎性腺发育过程中糖原和脂质的组织化学研究

为探讨不同育性长牡蛎(Crassostrea gigas)性腺发育过程中主要供能物质的利用和变化差异,利用过碘酸雪夫氏染色(PAS染色)和油红O染色法对不同育性三倍体长牡蛎及二倍体长牡蛎性腺组织进行观察分析。结果显示,增殖期,二倍体和三倍体长牡蛎性腺结缔组织中均含有大量糖原和脂质。随着性腺发育,二倍体和可育型三倍体(3nα型)长牡蛎性腺结缔组织中糖原含量明显下降,到成熟期几乎检测不到糖原,说明性腺结缔组织中的糖原为配子发生提供能量。脂质主要存在于性腺结缔组织和卵母细胞的细胞质中,说明脂质是卵细胞发育的重要组成物质。雌性二倍体和3nα型长牡蛎性腺结缔组织中的脂类含量随着性腺发育并未发生明显下降,推测糖原可能转化为脂质以满足性腺发育的物质需求。脂质在二倍体雄性长牡蛎的性腺发育过程中出现明显的减少,说明脂类在雄性性腺发育中的主要功能可能是供能而不是结构组成。糖原和脂类作为长牡蛎性腺发育过程中重要的供能和组成物质,在不育型三倍体(3nβ型)长牡蛎性腺发育过程中含量没有发生明显的变化,这与3nβ型配子发生受阻密切相关。推测3nβ型长牡蛎由于配子发育受阻,性腺发育初期积累的糖原和脂质并未分配至生殖细胞,而留在结缔组织中,从而使其在繁殖季节仍然能够保持快速生长。研究结果为牡蛎生殖发育调控机制及育性控制育种提供重要信息。     

壳聚糖固定化胰蛋白酶制备牡蛎肽的研究

以壳聚糖为载体固定化胰蛋白酶,制备牡蛎肽,然后以肽得率为指标,分别研究了pH值,酶加量,酶解时间和温度等单因子对固定化胰蛋白酶酶解牡蛎蛋白质的影响。实验结果表明,酶解牡蛎蛋白的最佳工艺条件是:底物浓度为200μg/mL,加固定化胰蛋白酶量7mg/3mL,酶解时间3h,pH 8.0,温度40℃。在此条件下水解牡蛎蛋白,肽得率可达到20.39%。     

冬季单体牡蛎池塘育肥初步实验

为提高牡蛎商品品质,开展了池塘葡萄牙牡蛎(Crassostrea angulata)冬季育肥实验。育肥实验设置4个实验组:3组室内水泥池实验组(水温分别为24℃、20℃和16℃)以及1组室外池塘实验组,室内实验组饵料来自于室外池塘藻水。实验结果表明:经过一个月育肥,室外池塘实验组的牡蛎肥满度由13.1%增加到了19.6%,性腺饱满个体比例由13.3%增加到66.7%;室内水泥池实验组牡蛎肥满度无明显变化。池塘实验组牡蛎糖原含量稍有增加,水泥池实验组下降。池塘育肥葡萄牙牡蛎效果明显。     

Characterization,fluctuation and tissue differences in nutrient content in the Pacific oyster (Crassostrea gigas) in Qingdao,northern China

The Pacific oyster (Crassostrea gigas) is one of the most important aquaculture species worldwide. Its meat quality is vital for consumer satisfaction, and nutrient content, especially glycogen, is closely associated with oyster fatness and meat colour. Fluctuations in nutrient content of short‐term starvation have not been previously reported, and seasonal variation in glycogen content in different tissues has rarely been reported. In the present study, we investigated these important aspects of oyster production and found that short‐term starvation (50 hr) did not significantly alter glycogen, protein or lipid content. The seasonal variation assay showed that glycogen and lipid accumulation was high in autumn and winter and that seawater temperature and protein content were inversely related to glycogen content. Glycogen content of the whole flesh was higher from January to April and was positively related to the condition index before the onset of gametogenesis. Glycogen content was higher in the gonad, labial palp and mantle compared to the gill or adductor muscle. Relative expression of genes encoding proteins involved in glycogen metabolism (glycogen synthase, glycogen phosphorylase, glycogen debranching enzyme and glycogen branching enzyme) was closely associated with the glycogen content in the corresponding tissues. Glycogen content in the gonad was regulated by glycogen metabolic and glycolysis pathway genes (6‐phosphofructo kinase, phosphoglycerate kinase, pyruvate kinase, hexokinase and glucose transporters), and stored glycogen was the main energy source for gametogenesis. These findings contribute to oyster aquaculture management and glycogen improvement and expand our understanding of glycogen metabolism in oysters.     

牡蛎肉的醒酒作用机理初探

以小鼠血清中乙醇浓度为指标,对牡蛎肉中含有的蛋白质、糖原以及牛磺酸等生理活性成分的醒酒效果进行了初步探讨,旨在阐明牡蛎肉的醒酒作用机理.实验结果表明,牡蛎肉中的糖原和牛磺酸均具有明显的醒酒效果,最佳醒酒效果的剂量分别为0.8、0.05 mg/ml,与阳性对照组比较,小鼠血清的乙醇浓度分别下降了49.4%和43.74%,牡蛎肉蛋白质无醒酒作用,糖原和牛磺酸为牡蛎肉醒酒作用的主要有效成分.     

牡蛎的营养成分及蛋白质的酶法水解

研究了牡蛎肉的营养成分和其蛋白质的酶法水解。结果表明,牡蛎肉中蛋白质和糖原含量分别为50.63%和22.41%,其氨基酸组成完善,8种必需氨基酸占氨基酸总量的40%;537酸性蛋白酶比较适合于牡蛎蛋白质的水解,其优化的作用条件为:加酶量为1700U·g-1蛋白质、pH4、50℃、2h,在此条件下,水解液中的蛋白质和糖原提取率分别为78.23%和50.58%,水解液中的游离氨基酸和牛磺酸分别占总氨基酸的39.27%和12.47%。     

Heritability estimates for nutritional quality‐related traits of the Pacific oyster,Crassostrea gigas

Pacific oysters, Crassostrea gigas, are the most abundantly harvested shellfish in the world and are ecologically significant. The content of nutrients, including protein, glycogen, lipid, zinc (Zn), and selenium (Se), is important for oyster meat quality, but heritability estimates of such traits have rarely been reported. In this study, 64 full‐sib families were generated using a nested mating design. Finally, 18 full‐sib families, of which there were nine half‐sib families, with each containing 2 full‐sib families, were sampled for heritability estimates. The narrow‐sense heritabilities of glycogen, protein, lipid, Zn, and Se contents were 0.29 ± 0.02, 0.38 ± 0.02, 0.58 ± 0.08, 0.02 ± 0.02, and 0, respectively. Negative genetic correlations existed between both glycogen and protein content (?0.95 ± 0.004) and between lipid and protein content (?0.59 ± 0.05), whereas a positive correlation was observed between lipid and glycogen content (0.16 ± 0.06). Weak genetic and phenotypical correlations (r = 0–0.2) were observed between shell height and nutritional quality traits. These data demonstrated that glycogen, protein, and lipid content can be chosen in a selective breeding program, but glycogen and lipids cannot be selected together with protein. Furthermore, performing indirect selective breeding for quality traits by selecting traits related to growth is impossible. This study provides information for the development of breeding strategies for oyster quality traits.     

Experimental feeding of Sydney rock oysters (Saccostrea commercialis). III. Food concentration and fattening procedures

Sydney rock oysters (Saccostrea commercialis) were fed an artificial diet at 0, 3, 6, 9, 12 and 15 mg dry food/l. At 9 mg/l oyster glycogen content, condition indices and meat weight gains were maximised without increasing mortality rates. In a comparison of fattening procedures, oysters held in a fertilised pond and those fed a second artificial diet fattened in 4 and 6 weeks respectively, whereas those held in an estuary did not fatten at all. The artificial diet produced higher oyster meat glycogen contents than the fertilised pond and estuary treatments.     

捕后干露对3种贝类活品品质的影响

为明确经济养殖贝类捕后早期干露耐受性,选取活力良好的菲律宾蛤仔、长牡蛎和虾夷扇贝在4 ℃条件下进行8 d的无水贮藏,以闭壳肌pH、糖原、腺苷三磷酸(ATP)关联化合物、磷酸精氨酸的含量和奥品脱氢酶活性为指标,研究3种贝类的品质变化规律。试验结果表明,无水贮藏期间,菲律宾蛤仔pH无明显变化( P <0.05),而长牡蛎和虾夷扇贝pH分别由7.23和7.39降至6.88和6.80。3种贝的糖原含量均呈下降趋势。ATP在菲律宾蛤仔和长牡蛎初始含量仅为0.41、0.42 μmol/g,且贮藏过程无显著变化( P <0.05);在虾夷扇贝的初始含量为4.05 μmol/g,且随着贮藏时间延长急剧下降。虾夷扇贝和菲律宾蛤仔闭壳肌中章鱼碱脱氢酶活性最大,且随贮藏时间呈增加趋势。长牡蛎中alanopine脱氢酶和strombine脱氢酶起主要作用。结合主成分分析推定,长牡蛎、菲律宾蛤仔、虾夷扇贝对干露耐受时间分别是8、4、2 d。试验结果表明,在活贝捕后流通过程中应结合干露耐受性差异建立品种针对性的管理措施。     

Evaluation of three phytoplankton species as food for the pearl oyster <Emphasis Type="Italic">Pinctada fucata</Emphasis>

In the pearl cultivation farms of the Ehime Prefecture, Japan, mass mortalities of the pearl oyster Pinctada fucata have occurred since 1994. The occurrences of mass mortality roughly coincided with a shift of the dominant phytoplankton from Skeletonema and Chaetoceros to Chaetoceros and Nitzschia all of which belong to Bacillariophyceae. Hence, we evaluated Nitzschia, together with Chaetoceros and Isocrysis, as food for the oyster. Wet weights, lengths, widths, glycogen contents, and growth rates in terms of wet weight of the oysters in all the feeding treatments were significantly higher than those in the non-feeding treatment. The highest glycogen content (2.34%) and growth rate (2.21 g month⁻¹) were found in the Chaetoceros treatment. Growth rate in the Isocrysis treatment (1.63 g month⁻¹) was also high, although glycogen content in this treatment (0.41%) was low. In the Nitzschia treatment, growth rate of the oyster (0.94 g month⁻¹) was the lowest and glycogen content (0.83%) was also low relative to that in the Chaetoceros treatment. Chlorophyll a concentration in fecal pellets was lowest in the Nitzschia treatment (<2.7 μg mg⁻¹), suggesting more complete digestion of Nitzschia by the oyster. Thus, Nitzschia was edible and digestible but not assimilated by P. fucata. We propose the following scenario for the relationship between Nitzschia dominance and mass mortality. When Nitzschia dominates in a culture area, the physiological condition of P. fucata deteriorates due to low assimilation of Nitzschia by the oyster, followed by susceptibility of the oyster to infection by agents lethal to the oyster.     

香港牡蛎不同育肥方式的育肥效果

香港牡蛎营养丰富,味道鲜美,在上市前会通过集中育肥提高风味口感和经济价值。为探明不同育肥方式对香港牡蛎的育肥效果,对经过池塘育肥和外海育肥后香港牡蛎的壳高、壳长、壳宽、体质量、软体质量、出肉率、糖原含量、甜菜碱含量、蛋白含量等指标进行检测,并与内海对照组牡蛎进行比较分析。检测结果显示,经过池塘育肥,香港牡蛎的壳高、体质量、糖原含量和蛋白含量均显著升高( P <0.01),甜菜碱含量显著降低( P <0.01),壳长、壳宽、软体质量、出肉率无显著变化;经过外海育肥的香港牡蛎糖原含量显著升高( P <0.01),壳高、壳长、体质量、软体质量( P <0.01)和甜菜碱( P < 0.05 )含量显著降低,壳宽、出肉率和蛋白含量无显著变化。试验结果表明,池塘育肥比外海育肥效果要好;不论哪种育肥方式,育肥后牡蛎的糖原含量均显著升高,甜菜碱含量均显著降低,出肉率均无显著变化。     

微生物固定化载体筛选及其水质处理效果研究

为得到吸附能力强、水质处理效果良好的微生物固定化载体,本实验沸石、火山石、陶环、核桃壳、牡蛎壳五种不同载体对蜡样芽孢杆菌(Bacillus cereus,NY5株)的负载性能,以及在以养殖废水作为空白对照,游离NY5作为阳性对照的条件下,不同载体固定NY5对养殖的处理效果,并利用主成分分析法对水质处理效果进行综合评价。结果显示:沸石和牡蛎壳对NY5的负载性能较好,载菌量分别达1.25×10~9、9.0×10~8CFU/g;在养殖废水处理方面,火山石NY5组第7天、牡蛎壳NY5组第21天时NH_4~+-N浓度与空白对照相比分别降低53.4%、56.6%;火山石NY5组第7天时NO_3~--N浓度与空白对照相比降低87.9%;第28天时火山石NY5组、牡蛎壳NY5组NO_2~--N浓度与空白对照相比分别降低90.1%、80.2%;第14天时火山石NY5组TN浓度与空白对照相比降低51.6%。从主成分分析的结果也可以看出,火山石NY5组和牡蛎壳NY5组对养殖废水综合处理效果较好。