扁蓄提取物对小菜蛾生物活性的影响

研究扁蓄(Polygonum aviculare L.)乙醇提取物对小菜蛾(Plutella xylostella L.)触杀、胃毒、拒食及抑制生长的影响,比较扁蓄不同部位的活性,并对提取溶剂进行选择。结果表明,扁蓄乙醇提取物对小菜蛾的主要作用方式为触杀。     

金杯藤叶提取物的体外抗菌活性研究

[目的]对金杯藤叶的提取物进行体外抗菌活性测定及化学成分定性分析。[方法]用浓度85％乙醇作溶剂,采用微波辅助提取获得总提物,随后用石油醚、乙酸乙酯和正丁醇依次萃取;用纸片扩散法和微孔板二倍稀释法测定总提物及各萃取相对7种常见致病茵的抑茵圈、最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。用系统预试法初步测定叶提取物的化学成分。[结果]金杯藤叶总提物对表皮葡萄球菌、金黄色葡萄球菌及枯草芽孢杆菌有明显抗茵作用,而对铜绿假单胞菌、肺炎克雷伯氏茵、乙型副伤寒沙门氏茵、大肠埃希氏茵等无抗茵作用;其中石油醚相和水相对3种革兰氏阳性茵有抗菌活性。金杯藤叶可能含有糖类、多糖及苷类、皂苷、有机酸、生物碱、黄酮、甾体及三萜类和强心苷类等成分。[结论]金杯藤叶的总提物含多种生物活性物质,对革兰氏阳性菌有特异性抗菌活性,且有效成分存在于石油醚相和水相。     

藏沙蒿与多年生禾草混播对西藏沙化草地土壤酶活性和微生物生物量的影响

为分析藏沙蒿(Artemisia wellbyi)与多年生禾草混播3年的土壤酶活性和微生物生物量的含量特征,筛选出修复效果最好的混播比例,本研究采用比色和氯仿熏蒸的方法分别测定不同处理下的土壤酶活性和微生物生物量,以藏沙蒿、垂穗披碱草(Elymus nutans)和细茎冰草(Agropyron trachycaulhum)不同比例混播为处理,分别为T₁(4∶1∶2),T₂(4∶2∶1)和T₃(5∶1∶1),同时以未修复沙化草地为对照(CK),并与天然草地(NG)作比较。结果表明：与CK相比,3个比例混播处理均能改善土壤理化性质、提高土壤酶活性和微生物生物量碳氮磷含量,以T₃处理的效果最好。相关性分析表明,土壤酶活性与有机质、速效钾和全氮呈正相关;土壤微生物生物量与有效磷、碱解氮和含水量呈正相关。因此,灌草混播时,适当增加灌木的占比有利于土壤养分及生物学特性的恢复。     

钙对盐胁迫下水稻幼苗抗氧化酶活性和膜脂过氧化作用的影响

研究了外源Ca2 对盐胁迫下耐盐性不同的两个水稻品种(武育粳3号和IR36)几种抗氧化酶活性及膜脂过氧化的影响。结果表明:适量的Ca2 供应能有效提高水稻叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)以及抗坏血酸过氧化物酶(APX)的活性,使之维持在较高的水平上,并降低了丙二醛(MDA)含量和细胞膜透性。此外,外源Ca2 还增加了抗坏血酸(AsA)的含量,增强了水稻幼苗的根系活力。这表明适量的外源Ca2 供应提高水稻耐盐性的原因之一,在于其增强了植株的活性氧清除能力以及对细胞膜的稳定作用。     

Photosynthesis, symbiotic N and C accumulation in leaves of 30 nodulated cowpea genotypes grown in the field at Wa in the Guinea savanna of Ghana

Cowpea is a major food legume in Africa with relatively little information on N and C nutrition under field conditions in the continent. The aim of this study was to assess the relationship between leaf symbiotic N nutrition and photosynthetic carbon assimilation in cowpea genotypes grown under field conditions in the Guinea savanna of Ghana. The experiments were conducted in a randomized complete block design in Ghana, using 30 nodulated cowpea genotypes. Data collected from gas-exchange studies showed that genotypes with high photosynthetic rates expectedly exhibited greater stomatal conductance, high transpiration rates and increased water-use efficiency, leading to greater dry matter yield. In contrast, those with low photosynthetic rates revealed low stomatal conductance, low transpiration rates and low water-use efficiency. Quantification of symbiotic N in photosynthetic leaves indicated greater N₂ fixation in genotypes with higher photosynthetic rates, leaf transpiration and better water-use efficiency. Furthermore, measurement of C in leaves also indicated greater accumulation in genotypes with higher symbiotic N yield and total N, clearly indicating a link between C and N metabolism in photosynthetic leaves. Additionally, measures of photosynthetic N-use efficiency showed that genotypes with high levels of C-fixed per unit leaf total N also exhibited greater C-fixed per unit leaf N-fixed. Data suggest that where symbiotic legumes derive a large proportion of their N from N₂ fixation, photosynthetic C yield is much enhanced.     

Effects of dietary thiamin supplement on growth,body composition and intestinal enzyme activities of juvenile Jian carp (Cyprinus carpio var. Jian)

A total of 1050 juvenile Jian carp (Cyprinus carpio var. Jian) (8.20 ± 0.02 g) were fed diets containing seven graded levels of thiamin (0.25, 0.48, 0.79, 1.06, 1.37, 1.63 and 2.65 mg kg^?1) for 60 days to investigate the effects of thiamin on growth, body composition and digestive enzyme activities. Percent weight gain (PWG), feed intake and feed efficiency (FE) were the lowest in fish fed the basal diet (P < 0.05). Protein productive value and lipid productive value increased with increasing dietary thiamin levels up to 1.06 and 0.79 mg kg^?1 diet, respectively (P < 0.05). Body protein and lipid increased with increasing dietary thiamin levels (P < 0.05), while moisture and ash of fish carcasses decreased with the increase in dietary thiamin supplementation (P < 0.05). Intestinal folds height had a similar trend to PWG (P < 0.05). Activities of α‐amylase, lipase, trypsin, Na⁺, K⁺‐ATPase, alkaline phosphatase and gamma‐glutamyl transpeptidase in intestine were all affected by the dietary thiamin (P < 0.05). In conclusion, thiamin could improve growth and intestinal enzyme activities of juvenile Jian carp. The dietary thiamin requirement of juvenile Jian carp (8.0–60.2 g) based on PWG was 1.02 mg kg^?1 diet.     

小檗属植物中生物碱成分及药理活性研究概述

本文对小檗属植物的生物碱成分及药理活性等方面的研究进行了概述。研究结果表明,小檗属植物主要含有效成分为生物碱类物质,常见类型为原小檗碱型及双苄基异喹啉型生物碱;在药理活性方面,小檗属植物具消炎抗菌、降血压、降血糖、抗心律失常、抗癌等作用。     

饥饿与再投喂对褶皱臂尾轮虫几种消化酶活力的影响

25℃下就饥饿与再投喂对褶皱臂尾轮虫几种消化酶活力的影响进行了研究。结果表明：整个试验过程淀粉酶和纤维素酶活力一直保持较高水平。饥饿条件下,淀粉酶和纤维素酶活力在最初的1～2d下降最为明显,此后保持在一定水平;类胰蛋白酶和胃蛋白酶活力总体下降不大。饥饿条件下带卵率<0.09时,轮虫消化酶活力显著低于正常水平。恢复投喂1d后,褶皱臂尾轮虫带卵率从0增加到0.21,类胰蛋白酶和纤维素酶活力恢复正常水平,而胃蛋白酶和淀粉酶活力高于正常水平;活体观察显示褶皱臂尾轮虫胃和胃腺在再投喂1d内恢复正常结构。投喂条件下,这几种消化酶活力的高低与与带卵率大小没有直接关系。     

凝结芽孢杆菌对奥尼罗非鱼消化酶活性、消化率及生长性能的影响

在基础饲料中分别添加不同剂量的凝结芽孢杆菌(Ⅰ:1.0×1011cfu/kg饲料,Ⅱ:3.0×1011cfu/kg饲料,Ⅲ:6.0×1011cfu/kg),室外水族箱中饲养奥尼罗非鱼(Oreochromis niloticus×O.aureus)(34.50±0.25 g),用基础饲料投喂作为对照,每饲料组设三个重复,每水族箱随机放养16尾鱼,投喂率为3%。采用静水饲养以避免各箱之间水的交换。56 d后测定鱼体的生长和消化酶活性。结果显示:不同添加量的凝结芽孢杆菌均能显著提高奥尼罗非鱼胃、肝胰脏和肠道蛋白酶活性(P<0.05),但酶的活性随添加量的提高呈下降趋势。凝结芽孢杆菌的添加对胃、肝胰脏和肠道淀粉酶及脂肪酶活性没有显著影响(P>0.05)。Ⅰ组和Ⅱ组的干物质表观消化率、蛋白质消化率、相对增重率、饵料系数和蛋白质效率均显著高于对照组(P<0.05),而Ⅲ组和对照组之间差异不显著(P>0.05)。结果提示,饲料中添加1.0×1011cfu/kg饲料的凝结芽孢杆菌就能显著促进奥尼罗非鱼的生长和饲料营养物质的利用,满足最佳生长。     

饲粮中添加啤酒花渣对肉仔鸡肝和肾功能的影响

[目的]探讨啤酒花渣的饲用价值。[方法]各试验组肉仔鸡饲粮中分别添加0、4％、8％、12％、16％和20％啤酒花渣,研究啤酒花渣对肉仔鸡肝和肾功能的影响。[结果]各试验组肉仔鸡肝脏超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、总抗氧化能力（T-AOC）、谷胱甘肽过氧化物酶（GSH—Px）和丙二醛（MDA）差异均不显著（P〉0．05）。各试验组肉仔鸡肝脏和肾脏谷丙转氨酶（GPT）、谷草转氨酶（GOT）、乳酸脱氢酶（LDH）、胆碱酯酶（CHE）、醛缩酶（ALD）差异均不显著（P〉0．05）。[结论]饲粮中添加啤酒花渣对肉仔鸡肝和肾功能无不良影响。