返滴定法测定蜂胶中游离酸含量

建立测定蜂胶品中游离酸含量的方法.采用弱碱溶解蜂胶再酸化萃取的方法纯化样品,用返滴法测定,以水杨酸作为对照品检测样品中游离酸含量.结果测定了5个不同产地的蜂胶样品,游离酸含量在1.89～6.54%范围内,回收率为99.30%.本方法操作简单,重现性好,有助于蜂胶质量的鉴别.     

日粮脂肪酸组成对硬脂酰辅酶A去饱和酶的调控

硬脂酰辅酶A去饱和酶是体内饱和脂肪酸向单一不饱和脂肪酸转化的关键酶类,也是瘦素(Ob)基因通过信号传导发挥代谢生理调控作用的重要组分。其活性的高低关系到动物体脂肪酸的组成和瘦肉率的高低,进而影响产肉率和腌肉制品的产量,本文仅就日粮脂肪酸组成对该酶基因表达和酶活的调控进行综述。     

桑树内源激素及其生理效应的研究进展

综述了近２０年来桑树生长素、赤霉素、细胞分裂素、乙烯和脱落酸的研究进展。探讨了这五类激素在桑树生长发育和组织培养等方面的应用前景。     

Identification of lactic acid bacteria in the feces of dairy cows fed whole crop maize silage to assess the survival of silage bacteria in the gut

In order to assess the survival of lactic acid bacteria (LAB) in whole crop maize silage in the gut of dairy cows, one representative silage sample and three different feces samples were collected from dairy cows on three dairy farms in Hua Bei, China and three dairy farms in Kyushu, Japan. The composition of the bacterial community was examined by denaturing gradient gel electrophoresis and quantitative polymerase chain reaction. Lactobacillus acetotolerans was detected in all bunker‐made maize silage samples, regardless of the dairy farm or sampling region from which they were sourced. A total of eight LAB species were detected in the maize silage samples, of which three (L. acetotolerans, L. pontis and L. casei) appeared to survive digestion. The populations of L. acetotolerans in silage and feces were 10^6–7 and 10^3–4 copies/g, respectively, indicating that, even for the LAB species showing potential survival in the gut, competition in this niche may be harsh and the population may substantially decrease during the digestion process. It may be difficult for silage LAB to survive in the gut of silage‐fed dairy cows, because marked decrease in population can take place during the digestion process, even for surviving species.     

不同植物油对大规格吉富罗非鱼生长性能、组织脂肪酸组成的影响

本试验旨在探究大规格吉富罗非鱼(GIFT)对不同植物油的利用效果,筛选出大规格吉富罗非鱼饲料中合适的植物脂肪源。分别以大豆油(SO)、棕榈油(PO)、棉籽油(CO)、菜籽油(RO)、磷脂油(SL)和大豆油∶棕榈油∶棉籽油∶菜籽油∶磷脂油=1∶1∶1∶1∶1的混合油(MIX)为脂肪源配制6种等氮等脂的试验饲料,饲喂初始体重为(229.92±0.31)g的吉富罗非鱼8周。每种试验饲料投喂4个网箱(重复),每个网箱放养50尾。结果表明:对于增重率和特定生长率,棉籽油组和混合油组显著低于菜籽油组(P0.05)。菜籽油组饲料系数显著低于混合油组(P0.05),其他各组间无显著差异(P0.05)。混合油组蛋白质效率显著低于菜籽油组和磷脂油组(P0.05)。混合油组肝体指数显著高于棕榈油组和菜籽油组(P0.05)。大豆油组、菜籽油组、棕榈油组和磷脂油组在增重率、特定生长率和饲料系数方面没有显著差异(P0.05)。大豆油组和菜籽油组肌肉饱和脂肪酸总量显著低于其他各组(P0.05)。对于肌肉中n-3系脂肪酸/n-6系脂肪酸,菜籽油组显著高于其他各组(P0.05),棉籽油显著低于其他各组(P0.05)。棉籽油组肝脏饱和脂肪酸总量显著高于其他各组(P0.05),菜籽油组则显著低于其他各组(P0.05);对于肝脏n-3/n-6,菜籽油组显著高于其他各组(P0.05)。各组肌肉脂肪酸组成与饲料脂肪酸组成的相关系数均高于肝脏脂肪酸组成与饲料脂肪酸组成的相关系数。在饲料脂肪酸组成与肌肉或肝脏脂肪酸组成的相关系数中,均以棕榈油组最大,磷脂油组最小。由此得出,大豆油、棕榈油、菜籽油和磷脂油可以作为大规格吉富罗非鱼(体重为230~790 g)饲料中良好的脂肪源。大规格吉富罗非鱼肌肉中脂肪酸组成一定程度上被饲料脂肪酸组成影响,但肝脏脂肪酸组成与饲料脂肪酸组成的相关性较小。     

Effect of retinoic acid on gene expression profiles of bovine intramuscular preadipocytes during adipogenesis

To investigate genes involved in intramuscular adipogenesis in ruminants, 16 genes with dramatic variable expression were selected. These were selected from the differentiation‐ and proliferation‐phase libraries of our previous serial analysis of gene expression (SAGE) studies of a clonal bovine intramuscular preadipocyte (BIP) cell line. We harvested the BIP cells over 12 days after adipogenic stimulation with all‐trans retinoic acid (ATRA). Quantitative real‐time PCR confirmed the earlier SAGE study results of the expression patterns of 15 of the genes. On day 6, TG accumulation increased significantly in the BIP cells but was completely inhibited in the 3T3‐L1 cells (the monogastric reference). ATRA enhanced expression levels of six genes whereas it suppressed expression of eight genes on day 3 of adipogenesis in the BIP cells. Forty‐eight hours after transfection, the messenger RNA expression level of the adipose differentiation‐related protein (ADFP), encoded by one of the upregulated genes, in the ADFP small interference RNA (siRNA)‐transfected cells was 3.5% of that in negative control‐transfected cells. Also, 6 days after induction the TG level in the ADFP siRNA‐transfected cells was 21.8% lower than that in negative control‐transfected cells. This analysis of gene expression profiles after ATRA treatment will contribute to our understanding of the molecular mechanisms involved in bovine intramuscular adipogenesis.     

Investigation of the Role of Androstenedione-19-oic Acid in the Presence of 19-Norandrostenedione in Intact Male Horse Plasma Using Liquid Chromatography–Tandem Mass Spectrometry

A liquid chromatography–tandem mass spectrometry method was developed to confirm the presence of androstenedione-19-oic acid in intact male equine plasma and to show the source of 19-norandrostenedione in equine plasma. Androstenedione-19-oic acid was recovered from acidified plasma by liquid–liquid extraction using methyl tert-butyl ether and separated on an Ace 5 C₈ column. A triple quadrupole mass spectrometer was used to detect the analytes in negative electrospray ionization mode. Limits of detection, quantification, and confirmation of the method were 0.1, 0.5, and 1.0 ng/mL, respectively. The linear dynamic range of quantification was 0.5–50 ng/mL. The presence of androstenedione-19-oic acid was confirmed in all plasma samples obtained from intact male horses but not those from gelded and female horses; the average concentration was 3.1 ± 1.6 ng/mL, suggesting androstenedione-19-oic acid is an endogenous compound only in intact male horse plasma samples. The conversion of androstenedione-19-oic acid to 19-norandrostenedione in equine plasma was demonstrated by spiking androstenedione-19-oic acid into blank plasma and monitoring the generation of 19-norandrostenedione and its increase in concentration during storage. Results indicated that androstenedione-19-oic acid was readily converted into 19-norandrostenedione; the higher the storage temperature, the faster the conversion. The conversion was not affected by the types of plasma samples collected from gelded and female horses or by anticoagulants used in blood collection to harvest plasma. Compared with other matrices such as water, methanol, and phosphate-buffered saline, the conversion of androstenedione-19-oic to 19-norandrostenedione in equine plasma was faster, suggesting that there is an unknown factor(s) in equine plasma that enhances the conversion.     

Fatty acid patterns of dog erythrocyte membranes after feeding of a fish-oil based DHA-rich supplement with a base diet low in n-3 fatty acids versus a diet containing added n-3 fatty acids

Background

In dogs, increasing the tissue n-3 fatty acid (FA) content is associated with potential benefit in some medical conditions, e.g. atopic dermatitis, cancer or heart disease. Therefore effectively and conveniently increasing tissue n-3 FA levels in dogs is of interest. Incorporation of dietary n-3 FA into cell membranes may be studied by FA analysis of erythrocyte membranes (EM), because of the correlation of its FA composition with the FA composition of other cells. Aim of the study was to determine whether an n-3 FA additive added to a control diet is as effective in increasing EM n-3 FA content as feeding an n-3 FA enriched diet. Furthermore the time course of the incorporation of dietary n-3 FA into canine EM was investigated.

Methods

Thirty dogs were randomly divided into three dietary groups with ten dogs per group. CONT got a dry dog food diet which did not contain EPA or DHA. FO got a dry dog food diet with a high EPA and DHA content. ADD got the CONT diet combined with an n-3 FA additive rich in DHA and EPA. After a feeding period of 12 weeks the additive was discontinued in ADD and these dogs were fed CONT diet for another four weeks to observe washout effects. Erythrocyte lipids were extracted from venous blood samples and their FA composition was determined by gas chromatography. The Mann-Whitney-U-test was used to detect significant differences between the different groups and time points.

Results

After one week the proportions of n-3 FA, DHA and EPA were already significantly increased in ADD and FO, apparently reaching a plateau within eight weeks. In our study DHA and not EPA was preferably incorporated into the EM. After discontinuing the administration of the additive in ADD, the n-3 FA values declined slowly without reaching baseline levels within four weeks.

Conclusions

In dogs, an increase of dietary n-3 FA content leads to a rapid inclusion of n-3 FA into EM, regardless of whether the n-3 FA are offered as an enriched diet or as a normal diet supplemented with an n-3 FA additive.     

生长激素对蛋白质动态代谢与氨基酸利用的调控

生长激素是调节动物生长的众多激素中最重要的一种 ,它通过在肌肉与脂肪组织之间极强的营养重分配作用 ,增加体蛋白沉积 ,减少脂肪沉积 ,从而改变这两种组织的生长状况来实现其促生长功能。动物体内蛋白沉积是蛋白合成与降解同时进行的两个过程动态平衡的结果。本文综述了近年来有关生长激素对动物蛋白质动态代谢与氨基酸利用调控方面的研究结果 ,指出生长激素使蛋白质合成与降解速率均增加 ,整体蛋白质周转代谢强度加大 ,从而导致蛋白质沉积增加。