Effect of deamination reaction mediated by semicarbazide-sensitive amine oxidase on 3T3-L1 adipocytes

AIM: To observe the effect of the metabolites generated from oxidative deamination of methylamine (MA) or benzylamine (BZA) catalyzed by semicarbazide-sensitive amine oxidase (SSAO) on 3T3-L1 adipocytes. METHODS: 3T3-L1 preadipocytes were induced to differentiation. SSAO activity was determined by high performance liquid chromatography (HPLC) at different differentiation time points. MTT assay was applied to detect cell vitality after exposure to different concentrations of MA or BZA. Fluorescence probe DCFH-DA was used to determine the production of reactive oxygen species after incubation of 3T3-L1 adipocytes with MA or BZA. After exposure to 0.5 mmol/L MA or BZA for 4 h, malondialdehyde (MDA), total superoxide dismutase (T-SOD) and glutathione (GSH) in the adipocytes or preadipocytes were measured. RESULTS: SSAO activity increased with the increase in the differentiation days, and reached a maximum at the 8th day. Incubation of the cells with different concentrations of MA or BZA for 4 h did not significantly decreased the cell vitality (P>0.05). After exposure to 0.5 mmol/L MA or BZA, the reactive oxygen species in adipocytes significantly increased, and were about 3 to 4 times as compared with control group (P<0.05). After treatment with 0.5 mmol/L MA or BZA for 4 h, MDA content significantly increased, while the activity of SOD and the expression of GSH decreased in mature adipocytes compared with control group (P<0.05). However, MDA, T-SOD and GSH did not change significantly after treatment with equal molar of MA or BZA in the preadipocytes (P>0.05). CONCLUSION: MA or BZA induces oxidative stress in the mature adipocytes, which might result from the deamination products catalyzed by SSAO.     

Dietary glucose oxidase and/or catalase supplementation alleviates intestinal oxidative stress induced by diquat in weaned piglets

This study investigated the effects of dietary exogenous glucose oxidase (GOD) and/or catalase (CAT) on the intestinal antioxidant capacity and barrier function in piglets under oxidative stress. Sixty pigs assigned randomly to five treatment groups—CON: basal diet; DIQ: basal diet; GOD: basal diet + 40-U GOD/kg diet; CAT: basal diet + 50-U CAT/kg diet; and GC: basal diet + 40-U GOD/kg diet + 50-U CAT/kg diet—were analyzed. On Day 14, the CON group was injected with saline, and the others were treated with diquat. The results showed that in diquat-treated piglets, supplementation of dietary GOD and CAT elevated the superoxide dismutase and CAT activities and attenuated the malondialdehyde level in plasma and intestinal mucosa, enhanced the duodenal villus height and villus height/crypt depth ratio, upregulated ZO-1 mRNA level, and attenuated the apoptosis of the epithelial cells and caspase-3 mRNA level in the intestine. Additionally, the supplementation upregulated mRNA expression of the intestinal NF-E2-related factor 2-regulated genes in diquat-treated piglets. However, GOD combined with CAT could not alleviate oxidative damage better than supplementation of CAT or GOD alone under oxidative stress. Overall, the study provides a potential alternative that could relieve the weaning stress in piglets and help formulate antibiotic-free diets.     

C3,C4和CAM植物的光呼吸及有关酶活性的比较研究

对4种C_3植物和4种C_4植物,6种CAM植物的光呼吸的研究表明:C_4和CAM植物象C_3植物一样表现出断光后CO_2的猝发;它们的乙醇酸氧化酶活性远低于C_3植物,而过氧化氢酶活性略低于C_3植物;光下有乙醇酸的合成。我们认为在C_4和CAM植物中也存在光呼吸乙醇酸循环。C_4植物表观光呼吸的大小可能与其叶的解剖特征有关,而CAM植物的表观光呼吸可能与其代谢的昼夜节律变化有关。我们还研究了CAM植物的乙醇酸循环在早晨和傍晚的变化规律,发现绝大多数CAM植物的乙醇酸氧化酶活性、过氧化氢酶活性和乙醇酸的合成量都一致表现为傍晚高于早晨。我们认为CAM植物体内乙醇酸循环的运转傍晚较早晨快。     

表达葡萄糖氧化酶基因抗晚疫病马铃薯的培育

葡萄糖氧化酶催化分子氧氧化b-D葡萄糖产生葡萄糖酸和H2O2。产生H2O2和其它活性氧物质是植物对病原体侵入的防御反应。实验证明H2O2水平升高不仅可诱发细胞过敏坏死反应，而且还能激活抗病基因表达如植物抗毒素及诱导病原相关蛋白（PR）等基因的表达。通过农杆菌介导将来自黑麴霉（Aspergillus niger)的葡萄糖氧化酶基因转入2个马铃薯重要栽培品种大西洋（Atlantic)和夏普蒂（Shepody)中获得23个转基因株系，其中75％为Kan抗性植株。在23个转基因株系中有16个株系可用PCR扩增出目的基因。进一步用核酸斑点杂交选出13个杂交阳性株系。转基因植物总DNA的Southem blot分析表明，GO基因已整合到马铃薯四倍体基因组中，转基因大西洋植株中目的基因为2－4个拷贝，而夏普蒂转基因植株中为1个拷贝。将转基因植株离体叶妆种呼和浩特地区流行的Phytophthoro infestans的复合生理小种1，3，4孢子。结果表明，和未转基因对照组相比转基因植株病斑出现时间晚，病斑扩展速度慢，发病程度轻，感病叶片少。总体上表现出较明显抗病性。转基因大西洋中抗性株系多于夏普蒂。转基因马铃薯植株体内H2O2含量测定表明，转基因马铃薯植株的根系和叶片在KI－淀粉培养基上数天后变为蓝色，而未转基因对照植株的根系和叶片变化不明显。试验表明，转基因马铃薯植株对晚疫病的抗性和体风H2O2含量水平呈正相关。还对马铃薯转化中再生小植株诱导，转基因植株中GO基因拷贝数，对晚疫病抗性的鉴定以及表达葡萄糖氧化酶基因的转基因马铃薯产生抗性的机理等问题进行了讨论。     

培养料对黑木耳生育及多酚氧化酶活性的影响

以稻草和玉米芯为培养料,分别按比例加木屑栽培黑木耳(Auricularia auricula),结果表明,用稻草栽培黑木耳,产量随木屑比例增加有提高趋势,其木屑比例大小明显影响木耳的生育和多酚氧化梅的活性;用玉米芯栽培木耳,加木屑与否,其产量无显著差异,同时对木耳生育和多酚氧化酶活性影响也不明显。     

从细胞色素b基因序列探讨普氏野马与蒙古马的遗传多态性

测定了14匹普氏野马(6匹A系和8匹B系)和18匹蒙古马的细胞色素b基因全序列1 140 bp.分析了普氏野马和蒙古马之间的遗传多态性.从GenBank获得10个韩国Cheju马和2个日本家马细胞色素b全序列,以驴的序列作根,用最大简约化法绘制出45个序列的系统发育树.研究认为:普氏野马与蒙古马遗传关系较近;蒙古马具有多个起源或经过多次驯化;蒙古马、日本家马和韩国Cheju马具有共同的祖先.     

甜菜块根贮藏期间呼吸代谢的变化

以甜菜品种淮阴11号为材料。测定了在不同贮藏条件下甜菜块根呼吸强度、呼吸代谢的酶的活性及呼吸抑制剂的作用。试验结果表明,在温度处理15天以后,冻化贮藏的甜菜块根呼吸强度明显高于其它温度处理的甜菜。糖酵解和已糖磷酸途径抑制剂对呼吸强度的抑制百分比随贮藏时间的延长而加强,而三羧酸代谢途径的抑制剂(丙二酸)对呼吸的抑制程度较低且无明显变化。葡萄糖-6-磷酸脱氢酶活性在甜菜贮藏过程中逐渐加强,尤其是冻化贮藏的甜菜,其活性也明显高于琥珀酸脱氢酶活性。以上结果说明甜菜块根贮藏过程中,呼吸代谢既可通过糖酵解-三羧酸途径,也可通过己糖磷酸途径,且后者的作用随贮藏时间的延长而逐渐加强。另外,呼吸末端氧化是通过细胞色素氧化酶和过氧化氢酶,而贮藏后期多酚氧化酶活力则有明显的增强。     

白魔芋中多酚氧化酶活性测定及其护色研究

白魔芋在干燥脱水过程中发生酶褐变,影响魔芋粉的质量．研究了温度、pH值、底物浓度对白魔芋多酚氧化酶（Polyphenol Oxidase,PPO）活性的影响,设计了不同的护色方案,以确立白魔芋的最佳无硫护色条件．结果表明：白魔芋中PPO活性最适温度为35℃,在90℃以上的温度可以抑制白魔芋PPO活性;最适pH值为5.5,pH小于2和大于8时可以完全抑制PPO活性;L-半胱氨酸0.006%以上能有效地抑制白魔芋PPO的活性．     

辣椒ACC氧化酶基因部分序列的分离与鉴定

乙烯作为一种植物激素，在植物生长发育过程中发挥着重要的作用。1-氨基环丙烷-1-羧酸（ACC）氧化酶（ACO）是乙烯生物合成途径中的一种关键酶。本研究以辣椒为研究材料，根据报道的辣椒ACC氧化酶基因序列（AJ011109）设计引物，利用PCR的方法从中国种湘研4号基因组获得长度为354bp的gDNA序列和213bp的cDNA序列。利用生物信息学软件对所获得的gDNA和eDNA序列进行了分析。     

蔷薇科果树中山梨醇代谢的酶

介绍了参与山梨醇代谢的三种酶。6-磷酸山梨醇脱氢酶催化6-磷酸葡萄糖和6-磷酸山梨醇之间的可逆反应,主要存在于叶片中,对山梨醇的合成起重要作用,而几乎不参与山梨醇的氧化;山梨醇脱氢酶主要存在于果实中,在NAD~+或NADP~+存在下催化山梨醇向果糖或葡萄糖的转化;山梨醇氧化酶则氧化山梨醇转化为葡萄糖。这三种酶的性质和季节性变化具有不同特点。