不同品牌椰子汁质量的研究

为了更好地了解市售椰子汁的质量状况,本实验以市场上常见的20种不同品牌的椰子汁为样品,通过测量这20个样品的脂肪含量、可溶性固形物含量、蛋白质含量、酸价以及色差,分析了市售椰子汁的质量状况。结果发现:脂肪、可溶性固形物、蛋白质含量达到国家标准QB/T 2300-2006规定的均有19个样品;被测样品的酸价均值为0.86 mg/g,个别样品酸价较大,色差值(Lab值)的变化揭示了椰子汁在颜色上的差异。     

Characterizing the pigmented traditional rice cultivars grown in temperate regions of Kashmir (India) for free and bound phenolics compounds and in vitro antioxidant properties

The purpose of the research was to identify the phenolic and flavonoid compounds of seven different traditional pigmented whole rice cultivars grown in the temperate regions of Kashmir so as to study their relationship with in vitro antioxidant capacities. The completely pigmented rice cultivars were found to have higher phenolic, flavonoid, anthocyanin contents and exhibited higher antioxidant capacities than the light colored and sparely colored rice cultivars. A total of 40 compounds had been identified in the analyzed rice cultivars that were found to be distributed in 6 major categories with 6-phenolics, 6-flavonoids, 11-hydroxycinnamic acid derivatives, 7-hydroxybenzoic acid derivatives, 3-anthocyanins and 7-flavonoid glucosides of different flavonoid compounds. Among the free and bound fractions for each cultivars the light and sparsely colored depicted higher content of phenolics and in vitro antioxidant properties in bound faction, while the completely pigmented cultivars showed higher antioxidant properties in free fractions. The anthocyanins quercetin-3-O-galactoside, cyanidin-3-O-rutinoside and pelargonidin-3-O-diglucoside had been identified by LC-MS existing in the free fractions of the analyzed rice cultivars whereas, the free fraction of acetone + H₂O possessed higher percentage of phenolic compounds as compared to methanolic extracts and bound fractions. The black colored cultivars possessed higher DPPH scavenging activity and lipid peroxidation inhibition.     

外源水杨酸诱导的部分甜瓜自毒作用相关基因的表达分析

以甜瓜(Cucumis melo)品种‘新银辉’为材料,采取根灌法,以水杨酸(10μmol/L)处理甜瓜幼苗,通过Real-Time PCR对叶片中部分自毒作用相关基因的表达量进行定量分析,以探究外源水杨酸诱导对甜瓜自毒作用的影响。结果显示,经外源水杨酸诱导后:(1)在催化苯丙烷类代谢途径的3个初始反应的蛋白酶编码基因中,PAL和C4H随处理后时间增加,呈逐渐上调趋势,但PAL比C4H更快响应胁迫,而4CL转录水平没有显著变化;(2)在类黄酮生物合成的3个关键酶的基因中,CHI、F3H均显示出不同程度的下调,CHS于处理后1 d略微上调,然后恢复至处理前水平;(3)两个转录因子基因WD40、R2R3-MYB分别在不同处理时间后显著下调;(4)WD40与CHI的表达相关性较高。据上述结果 ,水杨酸诱导后:(Ⅰ)CHI表达可能与转录因子WD40蛋白相关;(Ⅱ)WD40、R2R3-MYB与PAL、C4H、4CL、CHS间不存在简单、明确的调控关系;(Ⅲ)柚皮苷、表儿茶素、芦丁等甜瓜主要化感物质合成减少。     

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.     

Exogenous application of melatonin improves plant resistance to virus infection

In this study, melatonin (MEL)-mediated plant resistance to tobacco mosaic virus (TMV) was examined to study local infection in Nicotiana glutinosa and systemic infection in Solanum lycopersicum. Exogenous application of 100 µm MEL increased anti-virus infection activity to 37.4% in virus-infected N. glutinosa plants. The same treatment significantly reduced relative levels of virus RNA analysed by qRT-PCR and virus titres measured by dot-ELISA, and increased the relative expression levels of the PR1 and PR5 genes analysed by qRT-PCR, in virus-infected S. lycopersicum. MEL treatment induced considerable accumulations of salicylic acid (SA) and nitric oxide (NO) but did not significantly affect production of hydrogen peroxide (H₂O₂) in the virus-infected S. lycopersicum plants. Transgenic nahG N. tabacum was used to determine whether MEL-induced TMV resistance was dependent on the SA pathway. The results showed that the relative RNA level of the TMV analysed by qRT-PCR and virus titres analysed by dot-ELISA were not reduced by the MEL treatment in the nahG transgenic N. tabacum seedlings treated twice with 100 µm MEL. The increased relative expression levels of PR1 and PR5 were greatly reduced when cPTIO, an NO scavenger, was included in the MEL treatment. A working model of MEL-mediated plant resistance to TMV is proposed. MEL-mediated plant resistance to viruses provides a new avenue to control plant viral diseases.     

基于紫花苜蓿混播草地的全草型肉羊放牧育肥模式案例研究

本研究旨在探讨紫花苜蓿（Medicago sativa L.）混播草地放牧利用的生产潜力和集成全草型集约化肉羊放牧育肥技术模式。2017-2018年，在位于河北省廊坊市的中国农业科学院国际农业高新技术产业园内开展了2年羔羊育肥的划区轮牧试验，研究了紫花苜蓿混播草地的地上生物量、育肥羊增重以及羊肉品质的变化规律。结果表明：混播草地地上生物量超过11.2 tDM·hm^-2，5月份紫花苜蓿混播草地的粗蛋白为20.92%，每公顷紫花苜蓿混播草地可满足51只育肥羊、放牧育肥150天，每只增重30 kg所需的干物质、代谢能和粗蛋白三个方面的全部需求。与此同时，紫花苜蓿混播草地还可以显著增加羊肉中欧米伽3型多不饱和脂肪酸的含量，n-6/n-3比例为2.72，羊肉健康品质显著提高。以紫花苜蓿混播草地为基础的全草型肉羊放牧育肥技术具有广阔的应用前景，对我国苜蓿产业以及草地畜牧业发展具有重要意义。     

胡麻亚麻酸含量的遗传分析

亚麻酸是胡麻脂肪酸组成的主要成分,也是胡麻品质改良的主要目标。为深入研究胡麻亚麻酸含量的遗传规律,基于6个世代遗传群体(P_1、F_1、P_2、B_(1:2)、B_(2:2)、F_(2:3)),采用数量性状主基因+多基因混合遗传模型分析胡麻亚麻酸含量的遗传模式。结果表明,胡麻亚麻酸含量符合1对加性-显性主基因+加性-显性-上位性多基因遗传模型,主基因的加性效应在亚麻酸含量的遗传控制中具有重要贡献;B_(1:2)、B_(2:2)和F_(2:3)世代主基因遗传率分别为33.59%、46.95%和53.92%,多基因遗传率分别为25.60%、19.35%和14.43%;通过群体品质分析,筛选出高亚麻酸材料15份,高含油量材料7份,这些优异材料为胡麻品质育种奠定了良好的基础。     

不同产地西洋参氨基酸种类及含量分析

为研究不同种植区西洋参氨基酸的含量和品质，按食品安全国家标准GB/T5009.124-2016，对加拿大多伦多市、陕西省留坝县、吉林省抚松县、山东省文登市来源的4 a生西洋参进行氨基酸种类和含量测定及对比分析。各产地西洋参均检测出17种氨基酸，其中含有人体必需的赖氨酸、蛋氨酸、异亮氨酸、苯丙氨酸、亮氨酸、苏氨酸、缬氨酸和半必需氨基酸精氨酸；含有蛋氨酸、亮氨酸、异亮氨酸、苯丙氨酸、赖氨酸、天冬氨酸、甘氨酸、谷氨酸和精氨酸等8种药用氨基酸。人体必需氨基酸及药用氨基酸含量对比分析结果表明，加拿大多伦多市来源西洋参的这两类氨基酸含量最高，分别为46.20 mg/g 和61.93 mg/g，占总氨基酸含量的 54.0%和72.3%，其次是陕西省留坝县来源的西洋参，分别为45.70 mg/g和61.63 mg/g，占总氨基酸含量的51.9%和70.0%。主成分分析及综合评价结果表明，从氨基酸含量及营养均衡性角度来看，陕西省留坝县西洋参是最接近原产地加拿大的西洋参。     

Dietary taurine impacts the growth,amino acid profile and resistance against heat stress of tiger puffer (Takifugu rubripes)

A 56‐day feeding trail was conducted to evaluate the effects of taurine (Tau) supplementation on growth performance, amino acid profile and heat stress resistance capacity in juvenile Takifugu rubripes (initial body weight: 32.28 ± 0.20 g). Tiger puffer were distributed into five groups and each received one of the following diets: each diet was supplemented with 0 (T1), 5 (T2), 10 (T3), 20 (T4) or 50 (T5) g Tau/kg, respectively. Growth performances were significantly ameliorated with fed diet T3 (p < .05). The Tau content of muscle increased significantly as dietary Tau increased (p < .05). Compared to the control group, fish fed diets T4 and T5 showed significantly higher concentration of triglyceride and urea, respectively (p < .05), while taurine transporter (TauT) gene and IGF‐1 gene expression increased significantly in fish fed diets T3 and T4, respectively (p < .05). After acute heat stress, HSP70 gene expression levels were significantly greater in the livers and spleens of T. rubripes (p < .05) fed diet supplemented with Tau. Levels of complement C4 were highest in fish fed 10 g/kg Tau (p < .05). These data suggested that dietary supplemented with taurine indicated positive effects on growth performances, amino acid profile and resistance against heat stress for T. rubripes.     

Effects of dietary tryptophan levels and fish stocking density on immunological and antioxidant responses and bactericidal activity against Aeromonas hydrophila in rainbow trout (Oncorhynchus mykiss)

Rainbow trout (Oncorhynchus mykiss) was reared under low (LD) and high (HD) stocking densities for 70 days, during which they were fed with diets supplemented with 0, 5 and 10 g tryptophan (Trp) per kg. At the end of the experiment, there were significant interaction effects of the stocking density and Trp levels on plasma Trp, globulin, lysozyme, catalase (CAT), malondialdehyde (MDA), and bactericidal activity and blood leucocyte count. However, there was no difference in plasma complement (ACH50), total immunoglobulin (Ig), total antioxidant capacity (TAC), superoxide dismutase (SOD) and blood differential leucocyte count. Trp at 5 g per kg diet significantly increased lysozyme and bactericidal activity, and decreased MDA under both the LD and HD conditions. Moreover, it significantly increased plasma CAT and blood leucocyte under the LD and HD conditions respectively. Trp at 10 g per kg diet significantly increased blood leucocyte and plasma bactericidal activity under the LD condition, but significantly decreased plasma globulin and bactericidal activity under the HD condition. In conclusion, the present results showed that the effects of Trp on immune and antioxidant systems depend on Trp levels and stressful conditions. As 5 g Trp per kg diet is beneficial for rainbow trout well‐being under both the LD and HD conditions, higher level of Trp (10 g/kg) is not beneficial and even causes some negative effects under the HD condition.