Hypoglycemic effects and constituents of the barks of Cyclocarya paliurus and their inhibiting activities to glucosidase and glycogen phosphorylase

The various fractions of the barks of Cyclocarya paliurus were systematically tested for hypoglycemic effects in alloxan-induced diabetic rats. The results showed that the chloroform fraction of the 75% EtOH extract of the barks of this plant exhibited significant blood sugar reducing activity, most of which were significantly higher than that of positive-drug metformin hydrochloride. A new compound, together with nine known compounds, was isolated from the most active fraction. The structure elucidation was based on spectroscopic methods, including two-dimensional NMR experiments (¹H-¹H COSY, HMQC, and HMBC). All of the isolates were evaluated for their α-glycosidase and glycogen phosphorylase inhibitory activities.     

Low oxygen and 1-MCP pretreatments delay superficial scald development by reducing reactive oxygen species (ROS) accumulation in stored ‘Granny Smith’ apples

‘Granny Smith’ apples are highly susceptible to superficial scald, a symptom of chilling injury. For many crops, low temperature storage results in oxidative stress and chilling injury, caused by increased production of superoxide anions which in turn leads to the generation of other dangerous reactive oxygen species (ROS). Application, prior to cold storage, of low oxygen (LO2, <0.5%) atmospheres, ethanol (<2% vapour) or 1-methylcyclopropene (1-MCP, 0.5 μL L⁻¹) at 20 °C, was effective in reducing superficial scald in fruit following 24 weeks of cold storage. ROS levels were measured by confocal laser-scanning microscopy of apple peel treated with the fluorescent probe 2′,7′-dichlorodihydrofluorescein diacetate. In control fruit, ROS levels increased during cold storage and shelf-life and were very high after only 8 weeks, whereas in 1-MCP-, ethanol- and LO2-treated fruit, ROS levels remained low throughout storage. Gene-expression levels of ROS-scavenging enzymes were induced by the various pretreatments: catalase (MdCAT) was induced by LO2 treatment, whereas Mn superoxide dismutase (MdMnSOD) was induced by 1-MCP treatment. Polyphenol oxidase (MdPPO) gene expression levels were associated with scald symptom development and were highest in control fruit. Ethylene levels and expression of ethylene biosynthesis genes were correlated with α-farnesene levels and <alpha>-farnesene synthase (MdAFS) gene expression in the variously treated fruit. Accumulation of the α-farnesene oxidation product, 6-methyl-5-hepten-2-one (MHO), was highest in control fruit after 8 weeks, in accordance with ROS accumulation. The LO2 pretreatment mechanism might involve production of anaerobic metabolites, causing a delay in ethylene and α-farnesene biosynthesis and oxidation; this is different from the mechansism of action of 1-MCP, even though both consequently reduce ROS accumulation and scald symptoms.     

美式铁盘比萨饼的制作工艺研究

考察了发酵温度、发酵时间、真菌α-淀粉酶和葡萄糖氧化酶对比萨饼品质的影响,以确定比萨饼制作工艺的最佳条件。正交试验结果表明,制作比萨饼的最佳工艺条件:发酵温度为30℃,发酵时间为90 min,真菌α-淀粉酶添加量为4 mg/kg,葡萄糖氧化酶添加量为30 mg/kg。     

胸腺肽α1对猪瘟和猪蓝耳病疫苗免疫效果的影响

以注射疫苗同时注射胸腺肽α1（Tα1）的方式,研究Tα1对猪瘟和猪蓝耳病疫苗免疫效果的影响.结果表明：在与猪瘟疫苗联用时,Tα1可显著提高其抗体产生率;在与猪蓝耳病疫苗联用时,虽然没有显著提高抗体产生率,但可维持抗体的长效性表达.胸腺肽Tα1对猪瘟和猪蓝耳病疫苗的免疫效果具有调节功能,其调节机制有待进一步研究.     

TNF-α/IL-1α机制对破骨细胞形成和活化的影响

为了探讨肿瘤坏死因子α(TNF-α)/鼠重组白介素-1α(IL-1α)是否能独立于RANKL/RANK/ OPG机制之外直接刺激破骨细胞(OC)的形成和活化.提取4周龄C57雌性小鼠脾细胞,加入鼠巨噬细胞集落刺激因子(M-CSF)TNF-α(±IL-1α)进行体外培养,同时加入骨保护素(OPG)和可溶性NF-κB受体活化子配体(sRANKL)以区别RANKL/RANK/OPG机制.通过OC形态学观察、抗酒石酸酸性磷酸酶(TRAP)染色、骨吸收陷窝方法鉴定OC的形成和活化水平.结果显示:TNF-α(±IL-1α)能诱导睥细胞融合产生TRAP阳性的多核细胞并在象牙片上产生吸收陷窝,加入OPG不能阻断其诱导破骨细胞形成和产生骨吸收陷窝.结果表明:在MCSF存在的情况下,TNF-α以一种独立于RANKL/RANK/OPG之外的机制诱导破骨细胞的形成和活化,而且IL-1α能显著促进TNF-α的诱导作用(P＜0.05).     

卡拉库尔羊TNF-α基因原核表达载体的构建及表达条件优化

利用反转录PCR (RT-PCR)技术扩增卡拉库尔羊肿瘤坏死因子α(TNF-α)基因,连接到pET-28b载体,转化大肠杆菌BL21(DE3),在不同的IPTG浓度、时间、温度条件下诱导TNF-α的表达.结果表明,原核表达栽体pET-28b-TNF-α构建成功,可在大肠杆菌BL21(DE3)中诱导表达,优化的诱导表达条件为诱导温度37℃、诱导时间4h、IPTG浓度1.0 mmol/L.     

Adipose tissue and muscle fatty acid profiles of steers fed red clover silage with and without flaxseed

The current study examined the effects of inclusion of flaxseed in a red clover silage diet on growth, carcass quality, adipose tissue and muscle fatty acid (FA) profiles of beef steers. Twelve British×Continental crossbred steers (363±26.5 kg) were randomly assigned to two pens and fed diets containing 70% red clover silage, 15% steam rolled barley/vitamin–mineral supplement and either additional 15% steam rolled barley or 15% triple rolled flaxseed (all DM basis) for 215 d. Diet had no effect (P>0.05) on average daily gain or carcass quality atributes. Overall, FA profiles in all tissues followed similar trends when flaxseed was added to the diet but intramuscular fat had the highest proportions of n-3 and n-6 polyunsaturated FA (PUFA) while subcutaneous fat had largest proportions of conjugated linoleic acids (CLA) and perirenal fat had the highest proportions of trans-18:1 isomers, particularly vaccenic acid (VA). Feeding flaxseed increased (P<0.05) percentages of α-linolenic acid (ALA; 1.1–1.6% of total FA), total n-3 PUFA, conjugated linolenic acids, non-conjugated linoleic acids (mostly t11,c15-18:2), and led to unprecedented increases in CLA (mainly rumenic acid, RA; 1.1–2.9%), and trans-18:1 isomers (chiefly VA; 5.9–9.5%) in muscle and adipose tissues. Flaxseed also reduced individual and total n-6 PUFA, cis-monounsaturated FA, branched-chain FA and saturated FA (mainly 16:0) in beef lipids. Overall, feeding flaxseed in a red clover silage diet enhanced the levels of FA with a positive health image (ALA, 2-fold; RA, 3 to 4-fold and VA, 4 to 5-fold) and reduced the levels of less desirable FA (n-6 PUFA; 14:0, 16:0) in muscle and adipose tissues without adverse effects on growth and carcass quality. Differences in tissue FA composition were also noted, and high levels of VA in perirenal fat in particular have potential for use in testing for health effects and development of value added beef and other food products.     

Effect of pH and ethanol content of solvent on rheology of zein solutions

Zein, a corn protein, is a mixture of the polypeptides α-, γ-, β-, and δ-zein. α-Zein and γ-zein comprise 70–85% and 10–20% of total zein mass, respectively. Both peptides have similar amino acid composition, except γ-zein is rich in cysteine. The presence of cysteine has been associated with gelation of zein solutions. A common solvent for zein is aqueous ethanol. Preliminary results suggested that pH and ethanol content affect the rheology of zein solutions. Our objective was to investigate the effect of ethanol content (65–90%) and pH of the solvent (2, 6, and 12) on rheological properties of zein solutions (20% w/w) containing γ-zein. Steady shear tests and oscillatory time sweeps were performed to determine flow behavior and gelation time of zein solutions. Results indicated that α-zein solutions were nearly Newtonian while those containing γ-zein showed shear thinning behavior. At high pH, γ-zein increased the consistency index (K) and shortened gelation time. Results were attributed to the cysteine in γ-zein. High pH promoted formation of disulfide bonds leading to higher K values and shorter gelation times. Results of this work are expected to be useful in the design of zein extraction processes and the development of new zein applications.