糖的种类对海参蛋白美拉德反应产物性质影响研究

以海参蛋白为研究对象,分别选择葡萄糖、果糖、乳糖、麦芽糖、葡聚糖为糖源,探究糖的种类对海参蛋白美拉德产物性质的影响,并对海参蛋白与糖在不同反应时间和pH条件下所得产物性质进行分析。通过接枝度、溶解性和乳化性的测定,得出接枝度大小依次为葡萄糖、乳糖、麦芽糖、果糖和葡聚糖糖化产物,溶解性整体基本随pH和反应时间的增大呈上升趋势,乳化性随反应时间的延长明显提高。基于傅里叶变换红外光谱和差示热量扫描法对不同种类糖和海参蛋白的美拉德反应产物的进行结构表征,结果表明,海参蛋白在糖化反应后3348 cm^(-1)附近的峰向低波数发生了移动,移动的大小为葡萄糖<果糖<乳糖<麦芽糖<葡聚糖,说明糖化过程中发生了氢键缔合,同时海参蛋白美拉德产物的变性峰温度有所提高,稳定性增强。本研究为海参的高值化利用提供基础数据支撑。

海参蛋白肽对H_2O_2诱导RAW264.7细胞氧化损伤的保护作用

以海参为原料,研究海参蛋白肽的抗氧化性以及对H2O2诱导RAW264.7巨噬细胞氧化损伤的保护效果和作用机制。以清除羟自由基(·OH)能力、Fe2+螯合能力和Fe3+还原能力为指标,评价海参蛋白肽的体外抗氧化活性。以H2O2刺激RAW264.7巨噬细胞建立氧化损伤细胞模型,采用2′,7′-二氯荧光黄双乙酸盐(DCFH-DA)荧光探针法测定细胞活性氧(ROS)水平,四甲基偶氮唑盐(MTT)法测定细胞活力,实时荧光定量PCR测定细胞血红素氧合酶-1(HO-1)m RNA表达水平。结果表明,海参蛋白肽能够清除·OH,具有Fe2+螯合能力和Fe3+还原能力,海参蛋白肽的这种体外抗氧化能力呈现浓度依赖效应。海参蛋白肽显著降低氧化损伤RAW264.7巨噬细胞ROS水平和提高氧化损伤细胞活力(P<0.05)。而且,海参蛋白肽显著提高巨噬细胞内HO-1 m RNA表达(P<0.05),HO-1抑制剂锌原卟啉IX(Zn PPIX)部分逆转海参蛋白肽对氧化损伤巨噬细胞活力的促进作用。这些结果说明,海参蛋白肽通过上调RAW264.7巨噬细胞HO-1 m RNA表达水平,发挥对巨噬细胞氧化损伤的保护作用。

一株分解海参体壁蛋白的耐盐菌株的筛选及发酵条件优化

为获得可在高盐条件下降解海参蛋白的菌株,促进营养物质的释放,采用马丁氏培养基(高盐)从海水中分离获得3株可直接进行海参蛋白降解的耐盐菌株(SW01、SW02和SW03)。对降解能力最强的SW03,从形态学、生理生化特征及16S rDNA等方面进行了鉴定,探讨了菌株的最适降解条件,并与枯草芽孢杆菌(Bacillus subtilis)、解淀粉芽孢杆菌(Bacillus amyloliquefaciens)、植物乳杆菌(Lactobacillus plantarum)、肠膜明串珠菌(Leuconostoc mesenteroides)在各自最佳发酵条件下进行72 h发酵效果的比较。对发酵过程中发酵液pH、菌体浓度以及水溶性蛋白含量的变化进行了测定。结果表明,SW03为葡萄球菌属(Staphylococcus)菌株,其最佳发酵条件为26℃、接种量2.9%、初始pH 6.9。在此条件下,发酵液水溶性蛋白含量达到108.2 g/L。与其他4株商业菌株对比,SW03在进入稳定期后发酵液中菌体浓度及水溶性蛋白含量更高,且发酵过程中pH更稳定。耐盐菌株SW03在高盐环境下对海参蛋白有良好的降解作用,可作为海参蛋白降解菌株进行深入研究及开发。

Transcriptional changes in epigenetic modifiers associated with gene silencing in the intestine of the sea cucumber,Apostichopus japonicus(Selenka),during aestivation

The sea cucumber, Apostichopusjaponicus, undergoes aestivation to improve survival during periods of high-temperature. During aestivation, the metabolic rate is depressed to reduce the consumption of reserved energy. We evaluated the role of epigenetic modification on global gene silencing during metabolic rate depression in the sea cucumber. We compared the expression of epigenetic modifiers in active and aestivating sea cucumbers. The expression of three genes involved in DNA methylation and chromatin remodeling （DNA （cytosine-5）-methyltransferase l, Methyl-CpG-binding domain protein 2）, and Chromodomain-helicase-DNA-binding protein 5） was significantly higher during aestivation （Days 20 and 40）. Similarly, we observed an increase in the expression of genes involved in histone acetylation （Histone deacetylase 3） and Histone-binding protein RBBP4） during the early （Days 5 and 10） and late phases （Days 20 and 40） of aestivation. There was no change in the expression of KAT2B, a histone acetyltransferase. However, the expression of histone methylation associated modifiers （Histone-arginine methyltransferase CARMER and Histone-lysine N-methyltransferase MLL5） was significantly higher after 5 d in the aestivating group. The results suggest that the expression of epigenetic modifiers involved in DNA methylation, chromatin remodeling, histone acetylation, and histone methylation is upregulated during aestivation. We hypothesize that these changes regulate global gene silencing during aestivation in A. japonicus.

Construction of a cDNA library for sea cucumber Acaudina leucoprocta and differential expression of ferritin peptide

Acaudina leucoprocta is an edible sea cucumber of economic interest that is widely distributed in China. Little information is available concerning the molecular genetics of this species although such knowledge would contribute to a better understanding of the optimal conditions for its aquaculture and its mechanisms of defense against disease. Therefore, we constructed a c DNA library and, based on bioinformatics analysis of the sequences, the functions of 75% of the c DNAs were identifi ed, including those involved in cell structure, energy metabolism, mitochondrial function, and signal transduction pathways. Approximately 25% of genes in the library were unmatched. The gene for A. leucoprocta ferritin was also cloned. The predicted amino-acid sequence of ferritin displayed signifi cant homology with other sea-cucumber counterparts but indicated that it was a new member of the ferritin family. Semiquantitative real-time RT-PCR indicated the highest levels of ferritin m RNA expression in the intestine. A polyclonal antibody of ferritin was also produced. These data provide a set of molecular tools essential for further studies of the functions of ferritin protein in A. leucoprocta.

Growth, Metabolism and Physiological Response of the Sea Cucumber, Apostichopus japonicus Selenka During Periods of Inactivity

The growth, metabolism and physiological response of the sea cucumber, Apostichopus japonicus, were investigated during periods of inactivity. The body weight, oxygen consumption rate (OCR), activities of acidic phosphatase (ACP), alkaline phosphatase (AKP), catalase (CAT) and superoxide dismutase (SOD), and content of heat shock protein 70 (Hsp70) in the body wall and coelomic fluid of A. japonicus were measured during starvation, experimental aestivation and aestivation. The results showed that the body weight of sea cucumber in the three treatments decreased significantly during the experimental period (P < 0.05). The OCR of sea cucumber reduced in starvation and experimental aestivation treatments, but increased gradually in natural aestivation treatment. The activities of ACP and AKP of sea cucumber decreased gradually in all treatments, whereas those of SOD and CAT as well as Hsp70 content decreased in the starvation and experimental aestivation treatments and increased in natural aestivation treatment. The sea cucumber entered a state of aestivation at 24℃. To some extent, the animals in experimental aestivation were different from those in natural aestivation in metabolism and physiological response. These findings suggested that the aestivation mechanism of A. japonicus is complex and may not be attributed to the elevated temperature only.

Amino Acid Composition and Functional Properties of Giant Red Sea Cucumber (Parastichopus californicus) Collagen Hydrolysates

Giant red sea cucumber (Parastichopus californicus) is an under-utilized species due to its high tendency to autolysis.The aim of this study was to evaluate the functional properties of collagen hydrolysates from this species.The degree of hydrolysis (DH),amino acid composition,SDS-PAGE,emulsion activity index (EAI),emulsion stability index (ESI),foam expansion (FE),and foam stability (FS) of hydrolysates were investigated.The effects of pH on the EAI,ESI FE and FS of hydrolysates were also inves-tigated.The results indicated that the β and α1 chains of the collagen were effectively hydrolyzed by trypsin at 50℃ with an En-zyme/Substrate (E/S) ration of 1:20 (w:w).The DH of collagen was up to 17.3% after 3 h hydrolysis with trypsin.The hydrolysates had a molecular weight distribution of 1.1 17 kDa,and were abundant in glycine (Gly),proline (Pro),glutamic acid (Glu),alanine (Ala) and hydroxyproline (Hyp) residues.The hydrolysates were fractionated into three fractions (< 3 kDa,3 10 kDa,and > 10 kDa),and the fraction of 3 10 kDa exhibited a higher EAI value than the fraction of > 10 kDa (P<0.05).The fraction of > 10 kDa had higher FE and FS values than other fractions (P<0.05).The pH had an important effect on the EAI,ESI,FE and FS.All the fractions showed undesirable emulsion and forming properties at pH 4.0.Under pH 7.0 and pH 10.0,the 3 10 kDa fraction showed higher EAI value and the fraction of > 10 kDa showed higher FE value,respectively.They are hoped to be utilized as functional ingredients in food and nutraceutical industries.

Hpyerglycemic Effect of a Mixture of Sea Cucumber and Cordyceps Sinensis in StreptozotocinInduced Diabetic Rat

Sea cucumber and cordyceps sinensis are used as both food and traditional medicines in Asia. This study was carried out in order to investigate the hpyerglycemic effect of a mixture of sea cucumber （Apostichopusjaponicas） and cordyceps sinensis （Cor-dyceps militaris） （SCC） in diabetic rat and explore the mechanism underlining such an effect. The diabetic model rat was induced with intraperitoneal injection of streptozotocin （STZ）. The diabetic model rats were randomly divided into control group （0.9% NaC1）, low dose group （300 mg SCC.（kg body weight）-1） and high dose group （1200 mg SCC （kg body weight）-l）. Sodium chloride and SCC were intragastrically administered once a day for 35 d. Changes in fasting serum glucose and serum insulin content, oral glucose tolerance and liver and muscle glycogen content were routinely evaluated. Pancreas tissue and β-cells of islets were observed under both optical and transmission electronic microscope, respectively. The abundance of glucose metabolism-relating genes in gastrocnemius and epididymal adipose tissue was determined with either reverse transcription PCR （RT-PCR） or western blotting. Results showed that SCC significantly decreased fasting serum glucose content, improved glucose tolerance and increased serum insulin and glycogen content; repaired STZ-injured β-cells of diabetic rat, and increased the expression of phosphatidylinositol 3 kinase （PI（3）K）, protein kinase B （PKB） and glucose transporter 4 （Glut4） encoding protein in both gastroenemius and adipose tissue, and Glut4 encoding gene in peripheral tissue. Our findings demonstrated that SCC exerted an anti-hyperglycemic effect by repairing β-cells and promoting insulin-mediated signal transduction pathway in insulin-sensitive gastrocnemius and adipose tissue.

Effect of Food on Specific Dynamic Action(SDA) of Green and Red Types of Sea Cucumber(Apostichopus japonicus Selenka)

Specific dynamic action(SDA), the energy expended on all physiological processes that is associated with meal digestion and absorption, is strongly affected by food type. Effects of formulated diet(FMD), macroalgae(ALG) and sea mud(SMD) diets on the postprandial metabolic response of the green type and the red type of sea cucumber(Apostichopus japonicus) were studied in order to understand their feeding physiology. Food offered to A. japonicus was different in protein, lipid content and energy but not in meal mass. SDA of A. japonicus resulted in a 1.3–2.7 folds of increase in oxygen consumption that can persist for up to 4.8–31.7 h after digesting three different diets. In a given type of sea cucumber, the magnitude of SDA was the highest when fed with FMD, medium with ALG, and the lowest with SMD, which is probably due to the differences in diet components and protein contents. The red type sea cucumber showed greater SDA magnitude than the green type with each diet treatment, which might result from the difference in factorial scope between the two types of sea cucumber. However, the smallest magnitude or even no difference was observed between the two types of A. japonicus in SMD group, perhaps owing to the poor nutrition and digestion of sea mud.

Expression responses of five cold tolerant related genes to two temperature dropping treatments in sea cucumber Apostichopus japonicus

Environmental conditions, including ambient temperature, play important roles in survival growth development, and reproduction of the Japanese sea cucumber, Apostichopus japonicus. Low temperatures result in slowed growth and skin ulceration disease. In a previous study, we investigated the effect of low temperature on gene expression profiles inA.japonicus by suppression subtractive hybridization （SSH）. Genes encoding Ferritin, Lysozyme, Hsp70, gp96, and AjToll were selected from a subtracted cDNA library of A. japonicus under acute cold stress. The transcriptional expression profiles of these genes were investigated in different tissues （coelomocyte, respiratory tree, intestine, longitudinal muscle） after exposure to acute and mild temperature dropping treatments. The results show that （1） the five cold-tolerance-related genes were found in all four tissues and the highest mRNA levels were observed in coelomocyte and respiratory tree; （2） under the temperature dropping treatments, three types of transcriptional regulation patterns were observed： primary suppression followed by up-regulation at -2℃, suppressed expression throughout the two treatments, and more rarely an initial stimulation followed by suppression; and （3） gene expression suppression was more severe under acute temperature dropping than under mild temperature dropping treatment. The five cold-tolerance-related genes that were ,distributed mainly in coelomocyte and respiratory tissues were generally down-regulated by low temperature stress but an inverse up-regulation event was found at the extreme temperature （-2℃）.

淡干海参复水工艺

为探讨淡干海参在何种条件下复水其营养损失最少,并且仍然保持较好的口感,通过测定其复水后重量变化、海参复水液中的蛋白质损失量、质构等,在单因素试验的基础上进行正交试验,得出淡干海参最佳复水条件为:热烫温度85℃、热烫时间为10 min、保温复水温度为70℃,复水率为500.00%,复水时间为40~50 h。