橡椀单宁生物降解动力学研究

研究了微生物菌系对橡Wan单宁的生物降解能力。结果表明，其过程符合反应动力学方程L=Lmax(1-e^-k(t-t0)；并发现温度是影响降解速率的主要因素，在10-35℃范围内，温度升高，橡Wan单宁的生物降解速率相应样大，滞后期相应缩短；橡Wan单宁浓度对生物降解滞后期的影响，在低温时表现较显著，随温度的升高，这种影响减弱。     

植物单宁的营养学特性

结合植物单宁的化学性质，讨论了它们与蛋白质、酶、金属离子和多糖的作用。在此基础上，概述了植物单宁的抗营养性以及在食品和饲料加工中所采取的减弱单宁抗性的措施。     

内蒙古额济纳地区柽柳多酚含量及其生态作用研究

通过对生长于额济纳旗（极端干旱区）的特征植物多枝柽柳的枝条和根系中的植物多酚含量的研究发现：柽柳根系中的缩合单宁含量明显高于枝条中的含量，而且其含量在不同径级的根系中也有较大的差别，含量随着径级的增加而减少；就总酚含量来说，中根（Ф2—10mm）部分的含量较高，其它部位的含量接近。更为重要的是，植物体内的多酚含量与其土壤中的水分含量的相关性较强，表现为多酚含量与土壤中含水量呈现出较为明显的负相关，这一点在多枝柳的根系中表现得最为明显。我们推测，植物多酚在植物抵抗水分胁迫过程中起着关键性的作用，对植物维持其体内的正常生理活动起着至关重要的作用。     

Effects of log storage and drying on birch (<Emphasis Type="Italic">Betula pendula</Emphasis>) wood proanthocyanidin concentration and discoloration

In conventional drying, sawn birch (Betula sp.) timber darkens and reddens from the inside while the layer a few millimetres under the yellowish surface remains light in color. Lack of information concerning the chemical basis of the discoloration hinders the development of a reliable solution for this problem. In this study, the role of soluble proanthocyanidins in discoloration of birch wood was investigated because the polymerization and oxidation of these compounds are known to yield insoluble reddish compounds. Different periods of log storage affected the synthesis of soluble proanthocyanidins during conventional drying. Concentration of proanthocyanidins also correlated with changes in the color of birch wood. Discoloration appeared differently in conventionally dried and vacuum-dried wood, which indicates that the discoloration mechanism in these drying methods may differ chemically, and/or the compounds that take part in discoloration may be different at different drying temperatures.     

Condensed tannins in Leucaena and their relation to psyllid resistance

Leucaena species and hybrids were examined to determine the relative content of condensed tannins and its relationship to susceptibility to defoliation by the Leucaena psyllid (Heteropsylla cubana). The interspecific Leucaena hybrid KX2 (L. leucocephala × L. pallida) was examined for variability of condensed tannin levels. A broad range of condensed tannin values were found which indicate potential for improved forage value through selection for KX2 trees with lower condensed tannin while maintaining psyllid resistance. A significant correlation was not found linking condensed tannins and psyllid resistance.     

Development and validation of a robust KASP marker for zt2 locus in faba bean (Vicia faba)

Faba bean has the potential to become a key food and feed protein crop in many areas of the world. The presence of tannins in its seed coat has limited the deployment of this crop as feed and food. The expression of either of the two recessive genes, zt1 and zt2, causes a great reduction of tannins from the seed coat and results in a white flower phenotype. Molecular markers linked to these loci are fundamental tools for speeding up the breeding of low-tannin varieties. The main aim of this study was to develop and validate a robust molecular marker linked to the zt2 locus. We used 176 recombinant inbred lines of the Disco/2 × ILB 938/2 cross at F₆ and genotyped those using 257 SNP (single nucleotide polymorphism) markers. An SNP marker associated with zt2 locus was found on faba bean chromosome 3 and was used to develop a high-throughput low-cost KASP (kompetitive allele-specific PCR) marker. The KASP marker can successfully discriminate low-tannin faba beans carrying zt2 from those carrying zt1 and wild-type alleles.     

不同种质核桃中酚类物质及其抗氧化性的研究

本文以核桃为研究材料,通过采用DPPH自由基清除力、还原力、单宁、总酚和酚类物质为抗氧化指标,对8种不同地域和种质的核桃的抗氧化能力进行了比较。结果表明：陕西纸皮核桃的DPPH自由基清除率最强,河北薄皮核桃最弱;陕西纸皮核桃的还原力最强,山西薄皮最弱;总酚和单宁含量中,河北薄皮核桃最高,新疆纸皮最低; 酚类物质检测中芦丁含量最高。相关性分析结果表明酚类物质含量和核桃的DPPH自由基清除能力、还原力和单宁含量均有较高的相关性,这说明核桃中抗氧化活性物质主要为酚类化合物。此外,河北薄皮核桃和新疆薄皮核桃具有较强的抗氧化能力,益与人体健康,可为其品种选育和适用性的研究提供参考。     

Technical Note: The comparison of pH and redox potential in different locations in the reticulo-rumen of growing beef steers supplemented with different levels of quebracho extract

Rumen acidosis is a common metabolic disorder occurring when organic acid production exceeds clearance capacity, reducing ruminal pH. The occurrence of acidosis has been directly correlated to the ratio of concentrate to forage in the diet. However, rates of substrate fermentation and acid absorption vary at different locations in the reticulo-rumen. The objective of this study was to determine the pH and redox potential (Eh) in different locations of the reticulo-rumen using 16 ruminally cannulated steers (309 ± 43 kg) receiving different supplementation levels of quebracho extract (QT; Schinopsis balansae) within a grower type diet (CP: 13.4%; total digestible nutrients [TDN]: 70.4%; and ME: 2.55 Mcal/kg, dry matter [DM] basis). Animals were randomly assigned to one of four dietary treatments: QT at 0%, 1%, 2%, and 3% of DM (QT0, QT1, QT2, and QT3, respectively), containing about 0%, 0.7%, 1.4%, and 2.1% of condensed tannins (CT), DM basis, respectively. Animals were adapted to the basal diet for 12 d before being introduced to predetermined treatments for 4 weeks (wk), with diets provided twice daily to allow ad libitum intake. Weekly measurements of ruminal fluid pH and Eh were taken 4 h post-feeding using a portable pH meter with two probes (pH and redox) in four locations of the reticulo-rumen (reticulum, cranial sac, dorsal sac, and ventral sac). Data were analyzed using a random coefficients model with the pen as a random effect and wk as repeated measures, with DM intake included as a covariate. There was no interaction among treatments, location, and wk (P ≥ 0.882) on reticulo-ruminal pH. Overall, ruminal pH was lower for QT0 and QT1 compared to QT3 (P < 0.001). The pH in the reticulum was greater than those of the ventral and dorsal sacs (6.05 vs. 5.94, 5.89, respectively; P ≤ 0.001) but similar to cranial sac (6.00). Reticular pH was positively correlated with the ruminal locations (≥0.78; P < 0.001). The linear equation to estimate ruminal mean pH using reticulum pH had an intercept and slope different from zero (P ≤ 0.04), but CT (% DM) was not different from zero (P = 0.15), root mean square error of 0.15, and R² of 0.778: 0.723 (±0.36) + 0.857 (±0.059) × reticulum pH + 0.033 (±0.023) × CT. The Eh was lower for QT0 in week 1 than all other treatments (P < 0.001). We concluded that reticulo-ruminal pH differs among locations in the rumen regardless of QT supplementation level and days on feed, with reticular pH being the highest.     

水解单宁对凡纳滨对虾生长性能和肠道微生物的影响

为分析水解单宁对凡纳滨对虾生长及其肠道微生物菌群结构的影响,以基础饲料为空白组,在基础饲料中分别添加0.1%、0.2%和0.3%的水解单宁作为实验组,进行为期60 d的养殖实验后,统计生长性能,并取其肠道内容物提取DNA,用Illumina MiSeq测序平台进行16S rDNA基因V3～V4区高通量测序,检测对虾肠道内菌群结构及变化情况。结果表明:(1) 3个水解单宁添加组的增重率、特定生长率和肥满度与对照组相比均显著升高(P0.05),肝体比均显著降低(P0.05)。(2)4组样品中共获得206192条优化序列,操作分类单元(OUT)总数达542个。对照组凡纳滨对虾肠道微生物以变形菌门和蓝细菌门为主,其次是放线菌门和拟杆菌门;试验组肠道主要菌群为变形菌门、软壁菌门。试验组与对照组相比,蓝细菌门、放线菌门和拟杆菌门的比例降低,变形菌门、软壁菌门和厚壁菌门比例增加。(3)Rank-Abundance曲线和多样性指数结果可见,实验组的物种丰度和均匀度大体上均高于对照组。PCoA分析发现, 0.1%和0.3%添加组的微生物群落较为接近,而与0.2%添加组差别较大,结合生长性能指标可知,饲料中水解单宁的最适添加量为0.1%。以上研究表明,饲料添加水解单宁可显著改变对虾肠道的微生物组成,提高对虾生长速度,影响凡纳滨对虾的生长性能。     

Total phenolics and condensed tannins in field pea (Pisum sativum L.) and grass pea (Lathyrus sativus L.)

Seed samples of seventeen field pea cultivars grown at five locations, and nine grass pea lines grown at two locations, in western Canada during 1993 and 1994 were analysed for total phenolics and condensed tannins. Each location in each year was considered as one environment. Total phenolics in field pea differed significantly among cultivars, ranging from 162 mg/kg DM (dry matter) (CE, catechin equivalents) for AC Tamor to 325 mg/kg DM (CE) for Richmond. Field pea had barely detectable levels of condensed tannins. Total phenolics in grass pea ranged from 868 mg/kg DM (CE) for L880388 to 2059 mg/kg DM (CE) for LS89110. Condensed tannins in grass pea ranged from 0.89 g/kg DM (CE) for L880388 to 5.18 g/kg DM (CE) for LS89125. Cultivar had a larger relative contribution to total phenolic levels in field pea and to total phenolic and condensed tannin levels in grass pea than environment. Total phenolic and condensed tannin levels were not correlated with seed yield and seed protein content in field pea or grass pea. Levels of total phenolics and condensed tannins were positively correlated in grass pea. Grass pea seeds with darker seed coat colour contained higher levels of condensed tannins. This revised version was published online in July 2006 with corrections to the Cover Date.