氮沉降对植物-丛枝菌根共生体影响的研究进展

氮沉降是影响陆地生态系统的重要环境因子。丛枝菌根真菌(AMF)作为一种能够与绝大多数植物共生并广泛存在的土壤微生物,对植物生长、养分吸收以及抗逆性等均具有重要的调节作用,而针对氮沉降对植物-丛枝菌根共生体影响的研究往往被忽视。基于此,笔者从氮沉降对菌根侵染特性、菌根多样性、菌根对宿主植物生长发育、氮代谢、磷吸收以及对宿主植物生物多样性影响等方面进行了归纳总结,并提出应重点关注的研究方向,旨为菌根生理生态学的研究提供一定的科学依据。     

Effect of Mediterranean saltbush (Atriplex halimus) ensilaging with two developed enzyme cocktails on feed intake,nutrient digestibility and ruminal fermentation in sheep

The aim of this study was to assess the effects of feeding Atriplex halimus (AH) silage treated with two developed enzyme cocktails to sheep on feed intake, nutrient digestibility and ruminal fermentation. The AH silage was treated without or with 2 L of ZAD1^® or ZAD2^®/1000 kg with 5% molasses and ensiled for 30 days. Barley grain (300 g/head/day) was fed as an energy supplement once daily at 10.00 hours and AH silage with or without enzyme treatment was offered ad libitum to animals twice daily at 09.00 and 16.00 hours. Sheep were fed on four experimental forage diets comprised of AH silage and barley (D1), AH silage treated with ZAD1^® and barley (D2), AH silage treated with ZAD2^® and barley (D3) and AH silage treated with a combination of ZAD1^® and ZAD2^® (1:1) and barley (D4). Ensiling AH with enzymes reduced its contents of neutral detergent fiber and acid detergent fiber. The dry matter intake of AH of D2, D3 and D4 decreased (P < 0.001) as compared to D1. However, enzyme‐treated diets had greater total digestible nutrients intake (P < 0.001) as compared to D1. The nutrients digestibility for D2, D3 and D4 were higher than those for D1 (P < 0.001), and were higher for D3 as compared to both D2 and D4. Sheep fed on D3 had highest (P < 0.001) ruminal total volatile fatty acids concentration, ammonia nitrogen concentration and microbial protein yield. It could be concluded that AH silage treated with ZAD1^® or ZAD2^® improved digestibility and rumen fermentation in sheep.     

Effects of dietary energy level on lipid metabolism‐related gene expression in subcutaneous adipose tissue of Yellow breed × Simmental cattle

This study was conducted to estimate the effect of dietary energy level on lipid metabolism‐related gene expression of subcutaneous adipose tissue in Yellow breed × Simmental cattle. The experiment was conducted for 60 days. The results showed that final weight, average daily gain, average backfat thickness, (testicles + kidney + pelvic) fat percentage and subcutaneous fat percentage in the high and medium energy groups were significantly higher than in the low‐energy group but that the feed conversion ratio was significantly lower. The glucose, triglycerides, cholesterol, high‐density lipoprotein and low‐density lipoprotein in the high‐energy group were significantly higher than in the low‐energy group. With dietary energy increasing the activities of lipoprotein lipase (LPL), fatty acid synthase (FAS) and acetyl‐CoA carboxylase (ACC) significantly increased, whereas hormone‐sensitive lipase (HSL) and carnitine palmitoyltransferase‐1 (CPT‐1) significantly diminished. Peroxisome proliferator‐activated receptor γ (PPARγ), LPL, FAS, sterol regulatory element binding protein 1 (SREBP‐1), ACC, stearoyl‐CoA desaturase (SCD) and adipocyte‐fatty acid binding proteins (A‐FABP) gene expression were significantly increased by dietary energy increasing, and HSL and CPT‐1 gene expression were significantly decreased. These results indicated that with dietary energy increasing, the subcutaneous fat accumulation mainly increased due to adipose tissue lipogenic gene expression and decreased lipolytic gene expression.     

地衣芽孢杆菌对发酵床饲养仔猪生长性能、消化酶活性及肠道主要菌群数量的影响

本试验旨在研究发酵床饲养模式下日粮中添加地衣芽孢杆菌对仔猪生长性能、胰腺和小肠黏膜消化酶活性及肠道主要菌群数量的影响。选用108头体重13kg左右的35日龄健康苏钟猪,随机分为3组,每组3个重复,每个重复12头,分别饲喂基础日粮(对照组)、基础日粮+40mg/kg杆菌肽锌+20mg/kg硫酸黏杆菌素(抗生素组)、基础日粮+300mg/kg地衣芽孢杆菌(益生菌组)的试验日粮。预试期7d,正试期52d。结果表明:1与对照组相比,日粮中添加地衣芽孢杆菌能够在一定程度上提高仔猪平均日增重、平均日采食量,降低料重比,但各组间差异均不显著(P0.05)。2与对照组相比,日粮中添加地衣芽孢杆菌能够极显著提高仔猪胰腺中淀粉酶活性、十二指肠黏膜中麦芽糖酶活性和空肠黏膜中乳糖酶活性(P0.01),十二指肠黏膜和空肠黏膜中蔗糖酶活性显著提高(P0.05)。3与对照组相比,日粮中添加地衣芽孢杆菌能够显著提高仔猪盲肠芽孢杆菌数量(P0.05);乳酸杆菌数量较对照组提高4.09%,大肠杆菌数量较对照组降低4.86%,但均未达到显著水平(P0.05)。综上所述,在本试验条件下,日粮中添加300mg/kg地衣芽孢杆菌能够提高发酵床饲养仔猪胰腺、小肠黏膜消化酶活性及盲肠芽孢杆菌数量,同时仔猪生长性能也在一定程度上有所改善。     

苹果果实糖的研究现状

本文介绍了有关苹果果实糖代谢及相关酶的研究现状,并对影响苹果果实糖含量的因子进行了讨论。     

梭梭被肉苁蓉寄生后的生理代谢反应

在新疆吉木萨尔县林木良种试验站肉苁蓉良种繁育基地内,选择立地条件、梭梭树龄、林分密度、林木株行距、接种肉苁蓉方式以及管理措施等基本一致的梭梭人工林为试验地,以被肉苁蓉寄生、未被肉苁蓉寄生和曾被肉苁蓉寄生但已解除寄生关系的梭梭为研究对象,通过对梭梭同化枝的相对含水量、束缚水/自由水、叶绿素、脯氨酸、丙二醛含量等水分代谢和生化指标的测定,研究梭梭被肉苁蓉寄生以后的生理代谢反应.结果表明:与未被肉苁蓉寄生的以及曾被肉苁蓉寄生但采收了肉苁蓉种子的梭梭比较,被肉苁蓉寄生的梭梭同化枝的相对含水量有所降低,而束缚水/自由水的比值有所提高;与此同时,被肉苁蓉寄生的梭梭同化枝的叶绿素含量降低,而脯氨酸和丙二醛含量有所提高.三者之间的各项测定指标的差异达到显著程度.梭梭被肉苁蓉寄生以后引发的一系列生理代谢反应,既是梭梭被肉苁蓉寄生以后的一种生理代谢适应,也是引起被肉苁蓉寄生的梭梭生长衰退的主要原因之一.     

固定化酶载体的研究现状及其应用

研制开发性能优异的固定化载体,已成为固定化酶技术最为活跃的研究方向之一。固定化酶在生物及生物工程、环境化工、食品、医药等领域得以迅速发展,其中,结合现代分析仪器,固定化酶反应器(IMER)将成为固定化酶应用的一个新领域。本文对近几年来固定化酶载体的制备及固定化酶的应用进行了综述。     

干旱胁迫对白桦实生苗保护酶活性及脂质过氧化作用的影响

目前 ,活性氧自由基与植物抗逆性关系的研究正在日益深入 (戴金平等 ,1 991 ;王以柔等 ,1 995 ;许长城等 ,1 993;Ｊｏｈｎ ,1 992 ;Ｍａｒｃｅｌａｅｔａｌ.,1 993;阎秀峰等 ,1 999) ,对水分亏缺下活性氧对植物的氧化伤害及植物防御系统的反应也作了大量的研究 (陈立松等 ,1 998;1 999;沈秀瑛等 ,1 995 ;吕庆等 ,1 996;王爱国等 ,1 990 ;许长城等 ,1 993;阎秀峰等 ,1 999;Ｍｉｓｈｒａｅｔａｌ.,1 993)。在正常情况下 ,植物体内活性氧产生与清除处于平衡状态 ,不会导致细胞伤害 ,氧自由基的清除剂可分为酶促和非酶促两大类 (蒋明义等 ,1 996…     

Anti-inflammatory activities of cucurbitacin E isolated from Citrullus lanatus var. citroides: role of reactive nitrogen species and cyclooxygenase enzyme inhibition

The in vivo and in vitro mechanistic anti-inflammatory actions of cucurbitacin E (CE) (Citrullus lanatus var. citroides) were examined. The results showed that LPS/INF-γ increased NO production in RAW264.7 macrophages, whereas L-NAME and CE curtailed it. CE did not reveal any cytotoxicity on RAW264.7 and WRL-68 cells. CE inhibited both COX enzymes with more selectivity toward COX-2. Intraperitoneal injection of CE significantly suppressed carrageenan-induced rat's paw edema. ORAC and FRAP assays showed that CE is not a potent ROS scavenger. It could be concluded that CE is potentially useful in treating inflammation through the inhibition of COX and RNS but not ROS.     

Role of PPARα/PGC-1α in doxorubicin induced mouse dilated cardio-myopathy

AIM: To investigate the changes of peroxisome proliferator-activated receptors (PPAR)α/peroxisome proliferator activated receptor coactivator 1 alpha (PGC-1α) in doxorubicin (DOX) induced dilated cardiomyopathy (DCM) and its effect on the energy metabolism and myocardial function in mice. METHODS: Forty mice were randomly divided into 4 groups: control group, DOX group, PPARα inhibitor group and PPARα agonist group. The DCM model was established by injection of DOX. The protein levels of PPARα/PGC-1α were detected. The PPARα inhibitor and PPARα agonist were used 2 weeks beforeinjection of DOX. The contents of adenine acid and phosphocreatine (Pcr) in the mitochondria were measured by high-performance liquid chromatography (HPLC). The ANT activity was analyzed by the atractyloside-inhibitor stop technique. The changes of the echocardiography and hemodynamics were also observed. RESULTS: DOX induced DCM model was successfully established. The protein levels of PPARα and PGC-1α in control group were significantly higher than those in DOX group (P<0.05). Both of the high-energy phosphate contents and the transport activity of ANT were decreased in DOX group (P<0.05), and the hemodynamic parameters were disordered (P<0.01). Compared with DOX group, PPARα inhibitor pre-treatment significantly reduced the PPARα/PGC-1α expression. Meanwhile, high-energy phosphate contents in the mitochondria and the ANT transport activity of the mitochondria decreased, as well as the left ventricular function (P<0.05). On the other hand, PPARα agonist significantly increased the expression of PPARα and PGC-1α, and improved the transport activity of ANT. In addition, the hemodynamic parameters were ameliorated, but the high-energy phosphate contents of the mitochondria did not significantly change. CONCLUSION: PPARα/PGC-1α plays an important role in the regulation of ANT transport activity in dilated cardiomyopathy induced by DOX, and the activation of PPARα/PGC-1α has protective effects on the DCM induced by DOX.