Effects of dietary protein and lipid levels on growth performance,fatty acid composition and antioxidant‐related gene expressions in juvenile loach Misgurnus anguillicaudatus

Dojo loach (Misgurnus anguillicaudatus) is one of the most important cultured freshwater fish in several East Asian countries. However, a little information is available in its nutritional requirements. Thus, this study was conducted to evaluate the effects of feeding varying levels of dietary protein and lipid on growth, fatty acid composition and antioxidant‐related gene expressions in juvenile loach. Six practical diets at three levels of protein (30%, 40% and 50%) and two levels of lipid (6% and 12%) were fed to loach juveniles (initial weight 0.40 g) in triplicated groups (20 fish per replicated) for a period of 8 weeks. Results showed that regardless of lipid level, body weight gain of fish was significantly increased with incremental dietary protein level. Meanwhile, feed conversion ratio was significantly decreased by dietary protein levels, and the lowest value was observed in fish fed dietary protein levels of 50%, regardless of dietary lipid level. Moreover, the percentage of 22:6n‐3 in viscera was significantly increased by different protein levels. The expression level of catalase was significantly increased with incremental dietary protein level with both lipid levels. Meanwhile, the expression level of hepatic nuclear factor erythroid 2‐related factor 2 (Nrf2) was downregulated with incremental dietary protein level with 6% of lipid level, but the expression was upregulated with incremental dietary protein level with 12% of lipid level. In conclusion, these data suggested that 6% lipid and 50% protein in diet was optimal for loach during early development stage.     

Sorghum extrusion process combined with biofortified sweet potato contributed for high iron bioavailability in Wistar rats

This study aimed to evaluate the effect of sorghum and sweet potato on the bioavailability of iron, gene expression of proteins involved in iron metabolism and the plasma antioxidant capacity in animals fed with whole sorghum grains processed by dry heat or extrusion, combined or not with sweet potato flour with high content of carotenoids. Five experimental groups were tested (n = 7): dry heat sorghum flour (DS); extruded sorghum flour (ES); whole sorghum flour + sweet potato flour (DS + SP); extruded sorghum flour + sweet potato flour (ES + SP) and positive control (FS). The evaluations included: hemoglobin gain, hemoglobin regeneration efficiency, gene expression of divalente metal transporter 1 (DMT-1), duodenal citochroma B (DcytB), ferroportin, hephaestin, transferrin and ferritin and total plasma antioxidant capacity (TAC). The ES + SP group showed higher (p < 0.05) expression of DcytB, ferroportin and hephaestin when compared to the control group. The DS group showed high (p < 0.05) expression of DMT-1 and the ES showed high mRNA expression of transferrin and ferritin. The changes in the sorghum physicochemical properties from extrusion process reduced the iron and phytate content, and increased the gene expression of proteins involved in iron metabolism, improving iron bioavailability. The combination of sweet potato and sorghum flour (dry or extruded) improved the iron capture and total antioxidant capacity, probably due to the presence of β-carotene and antioxidant compounds.     

The heterogeneous distribution of α-amylase and endoxylanase activity over a population of preharvest sprouted wheat kernels and their localization in individual kernels

To develop targeted approaches to improve the quality of preharvest sprouted (PHS) wheat as a raw material for food manufacturing, knowledge on the nature and distribution of hydrolytic enzymes in PHS wheat is crucial. Results of the present study indicate that α-amylase and endoxylanase activities are heterogeneously distributed among a population of PHS kernel. Within individual severely sprouted kernels, the enzyme activities are heterogeneously distributed throughout the different tissues. α-Amylase activity, almost exclusively of endogenous nature, is mainly detected in the germ region and to a lesser extent in the aleurone layer. Endoxylanase activity is predominantly of microbial origin and located on the kernel surface. In spite of this, light and epifluorescence microscopy show decreased kernel integrity and cell wall breakdown in the crushed cells layer, the endosperm, and the aleurone layer in a selection of kernels upon preharvest sprouting. This knowledge offers opportunities for the development of treatments to reduce the enzyme load in PHS wheat at postharvest level to improve its flour quality.     

生物絮团对罗氏沼虾体组成和消化酶活性的影响

通过向养殖水体中泼洒糖蜜构建生物絮团养殖模式,分析生物絮团营养组成,并探讨生物絮团对罗氏沼虾体组成和消化酶活性的影响。试验分对照组和试验组(生物絮团组),其中试验组在养殖过程中泼洒糖蜜。试验在室内水泥池内(2 m×2 m×0.6 m)进行,每个处理有3个重复,每个重复225尾虾(0.26 g±0.02 g),试验周期为90 d。养殖过程中不换水,糖蜜的泼洒量根据饲料投喂量进行计算(C/N为20)。结果显示:添加糖蜜能够显著促进生物絮团的形成,到第90天时,试验组的絮团体积达21.22 mL/L;而对照组为6.03 mL/L;试验组絮团粗蛋白含量为29.47%,粗脂肪含量为4.32%,二者均显著高于对照组,而粗灰分含量为11.36%,显著低于对照组;泼洒糖蜜对罗氏沼虾体组成的影响不显著,对照组和试验组肌肉粗蛋白含量分别为21.09%和21.20%,粗脂肪含量分别为2.91%和3.06%;另外,向水体中泼洒糖蜜对罗氏沼虾消化酶活性影响显著。试验组罗氏沼虾肠脂肪酶活性、胃脂肪酶活性和胰脂肪酶活性均显著高于对照组;试验组罗氏沼虾糜蛋白酶活性、胰蛋白酶活性也均显著高于对照组。但泼洒糖蜜对肠淀粉酶、胃蛋白酶、胃淀粉酶、胰淀粉酶和纤维素酶活性没有显著影响。试验表明,生物絮团营养组成丰富,能够有效提高消化酶活性。     

火龙果茎多糖的超高压提取及抗氧化活性研究

为研究火龙果茎多糖的超高压提取工艺及抗氧化活性。在单因素试验基础上,采用Box-Behnken设计和响应面分析方法,确定超高压提取的最优工艺,并从清除ABTS自由基和DPPH自由基能力方面来评价火龙果茎多糖的体外抗氧化能力。结果表明,火龙果茎多糖的超高压提取的最佳工艺条件为:液固比10∶1(m L∶g)、超高压压力300 MPa、超高压时间4 min。在此工艺条件下多糖得率为(2.83±0.02)%。火龙果茎对ABTS自由基和DPPH自由基具有清除作用,对ABTS自由基和DPPH自由基的清除率IC_(50)分别为浓度为4.3 mg/m L和5.5 mg/m L时。     

饲料异亮氨酸水平对卵形鲳鲹消化酶活性和免疫指标的影响

实验旨在研究饲料异亮氨酸(Ile)水平对卵形鲳鲹(Trachinotus ovatus)消化酶活性和免疫指标的影响。以鱼粉、豆粕、花生粕和L-晶体氨基酸为蛋白源,配制含粗蛋白430 g·kg~(-1)的6种等氮饲料,各组分别含有13.2 g·kg~(-1)、15.7 g·kg~(-1)、18.2 g·kg~(-1)、20.7 g·kg~(-1)、23.2 g·kg~(-1)和25.7g·kg~(-1)(以干物质计)异亮氨酸。每组3个重复,每个重复随机放置20尾鱼[初始体质量(6.36±0.03)g],实验时长8周。结果显示,各实验组的肠淀粉酶和胃蛋白酶活性、血清总抗氧化能力(T-AOC)、溶菌酶(LZM)活性、免疫球蛋白M和补体(C3和C4)浓度均随着饲料Ile水平的升高而先上升后下降,这5个指标的较高值出现在18.2 g·kg~(-1)和20.7 g·kg~(-1)组,而较低值则出现在13.2 g·kg~(-1)和25.7 g·kg~(-1)组,上述4组与其他2组差异显著。血清尿素氮和丙二醛(MDA)浓度的变化趋势则与上述7个指标相反,较低值出现在18.2 g·kg~(-1)和20.7 g·kg~(-1)组,且显著低于其他4组。血清超氧化物歧化酶(SOD)活性则随着饲料Ile水平的增加而显著升高,18.2~25.7 g·kg~(-1)这4组SOD活性没有显著性差异。综上所述,饲料Ile水平为18.2~20.7 g·kg~(-1)时,卵形鲳鲹具有较好的消化性能和免疫机能。     

白藜芦醇对绵羊冷冻精液质量的影响

试验旨在研究白藜芦醇对绵羊冷冻精液质量的改善效果。采用假阴道法采集6只云南半细毛羊精液，用含不同浓度（0、0.1、1、10、20 μmol/L）白藜芦醇的Optidyl稀释液稀释后进行细管分装，低温平衡和液氮气相预冻后，在液氮中保存30 d。解冻后测定精子活力、质膜完整性、磷脂酰丝氨酸（PS）分布、顶体完整性和活性氧等指标。结果表明，解冻后10 μmol/L白藜芦醇组精子总活力、直线运动百分率、精子弯尾率分别为76.14%±0.97%、43.56%±0.91%、43.24%±1.68%，均显著高于其他各组（P<0.05）；而20 μmol/L白藜芦醇组精子总活力、直线运动百分率、精子弯尾率分别为21.78%±0.79%、25.23%±1.34%、4.84%±0.68%，均显著低于其他各组（P<0.05）。10 μmol/L白藜芦醇组精子顶体完整性最高，为50.47%±0.91%，显著高于其他各处理组（P<0.05）。PS分布结果表明，10 μmol/L白藜芦醇组正常精子百分率为46.43%±2.95%，显著高于20 μmol/L组（31.14%±3.56%，P<0.05），与其他各组无显著性差异（P>0.05）。20 μmol/L白藜芦醇组PS标记率（39.82%±3.38%）显著高于其他处理组（P<0.05）。活性氧试验结果表明，10 μmol/L白藜芦醇组正常精子（63.57%±0.71%）显著高于其他各组（P<0.05）；而20 μmol/L白藜芦醇组正常精子（32.45%±1.42%）显著低于其他各组（P<0.05）。综上，在冷冻稀释液中添加白藜芦醇可以改善绵羊冷冻精液品质，这与白藜芦醇的抗氧化特性有关。但是，白藜芦醇的冷冻保护效果具有明显的浓度依赖性，其最佳作用浓度为10 μmol/L，过高浓度的白藜芦醇反而加重精子的冷冻损伤。此外，对于白藜芦醇对绵羊精子的抗冻保护效果仍然需要体外受精或人工授精验证。     

粘虫高毒力白僵菌菌株筛选及其感菌后虫体内保护酶活性的变化

为获得生物学性状良好且对粘虫具有高毒力的球孢白僵菌菌株,本研究以8株球孢白僵菌(Beauveria bassiana)菌株为材料,根据菌株产孢量、萌发率和生长速率差异筛选优势菌株,然后测定优势菌株孢子悬浮液对粘虫3龄幼虫的致死率,以及3龄幼虫感染高毒力白僵菌后体内抗氧化酶和解毒酶活性的变化。结果表明,8株球孢白僵菌菌株生长特性各项指标均存在显著差异,菌株Bb314、Bb345、Bb412和Bb378的生长速率、产孢量和孢子萌发率高于其他4个菌株。菌株Bb314孢子悬浮液对粘虫3龄幼虫致死率最高,达69%。Bb314侵染粘虫后,感染前期虫体酚氧化酶(PO)和过氧化物酶(POD)活性显著提高,于36 h达峰值;过氧化氢酶(CAT)活性在感染初期(24 h)时低于对照,处理48 h后达到峰值,并显著高于对照;谷胱甘肽-S-转移酶(GSTs)和羧酸酯酶(CarE)活性分别在处理36 h和48 h后达到高峰,并显著高于对照。以上结果表明,菌株Bb314可能通过影响粘虫幼体内抗氧化酶和解毒酶活性的动态平衡,进而影响其生理代谢。本研究为开发粘虫生防菌的潜力菌株提供了参考。     

草酸处理对桂七芒果冷害及细胞壁代谢的影响

为探讨草酸处理对低温冷藏下芒果冷害及细胞壁代谢的影响,本试验以桂七芒果果实为试材,采用5 mmol·L^-1草酸溶液浸泡处理,以清水浸泡处理为对照,并于4℃贮藏,分析芒果的冷害指数、丙二醛(MDA)含量、相对电导率、硬度、细胞壁物质含量、细胞壁代谢酶的变化。结果表明,与对照组相比,草酸处理显著降低了低温贮藏14 d后桂七芒果果实冷害指数、MDA含量、相对电导率、原果胶和纤维素含量,显著降低了低温贮藏28 d后果实的硬度;显著提高了低温贮藏14 d后果实水溶性果胶含量及多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)、纤维素酶(Cx)活性,显著提高了贮藏21 d后果实β-半乳糖苷酶(β-Gal)活性。综上所述,草酸处理能减轻桂七芒果冷害,维持采后果实细胞壁降解酶较高活性和水溶性果胶含量。本研究为揭示草酸减轻芒果果实冷害机制提供了依据,可为草酸应用于其他冷敏型果实的贮藏保鲜提供理论参考。