采收时间对玫瑰茄萼片产量及营养成分的影响

为明确玫瑰茄最佳采收时间,以玫瑰茄种质M3和M5为试验材料,对不同采收时间玫瑰茄的萼片产量和原花青素、单宁等营养成分含量进行分析。结果表明,随着采收时间推迟,2份种质的萼片产量和营养成分含量均呈先增加后减少的趋势。M3的鲜果重、鲜萼片重均在开花后21 d达到最大值,分别为12.82 g和7.75 g,干萼片重在开花后28 d达到最大值,为0.98 g;M5的鲜果重在开花后21 d达到最大值,为6.97 g,鲜萼片重、干萼片重均在开花后28 d达到最大值,分别为3.90 g和0.47 g,以采收花萼为目的时,适宜采收期为开花后21~28 d。M3萼片的原花青素含量在开花后35 d时最高,达2 180.00 mg·kg^-1,M5在开花后21 d时最高,达573.50 mg·kg^-1,以提取原花青素为目的采收时,M3和M5的适宜采收期分别为开花后35 d和开花后21 d。M3的单宁含量在开花后28~35 d时最高,达2.30 g·kg^-1, M5在开花后42 d时最高,达1.38 g·kg^-1,以提取单宁为目的采收时,M3和M5的适宜采收期分别为开花后28~35 d和开花后42 d。综上,玫瑰茄的适宜采收时间为开花后一个月左右(28~35 d)。本研究可为玫瑰茄合理采收提供参考依据。     

基于DGGE和T-RFLP分析采食不同粗饲料梅花鹿瘤胃细菌区系

【目的】细菌区系在梅花鹿（Cervus nippon）瘤胃发酵中发挥着重要作用,然而有关梅花鹿瘤胃细菌区系的研究鲜有报道。研究梅花鹿瘤胃细菌区系,为梅花鹿瘤胃发酵调控提供分子生物学依据。【方法】选取4头2岁龄的装有永久性瘤胃瘘管的成年雄性梅花鹿为研究对象,分别饲喂以柞树叶（OL组,梅花鹿A和B）和玉米秸秆（CS组,梅花鹿C和D）为主要粗饲料的日粮,持续饲喂30 d。通过瘤胃瘘管取瘤胃内固液混合物,提取瘤胃微生物基因组DNA。扩增瘤胃细菌16S rRNA基因V3区以及16S rRNA基因,分别用于DGGE和T-RFLP分析。DGGE图谱进行聚类分析,并切取优势条带进行克隆测序,鉴定瘤胃内细菌组成。根据T-RFLP图谱结果计算细菌群落的多样性、优势度、均匀度和丰富度,通过Microbial Community AnalysisⅢ（MiCAⅢ）数据库推测T-RFs可能代表的微生物种类,并进行T-RFLP图谱的聚类分析。【结果】DGGE图谱聚类表明,CS组和OL组瘤胃细菌区系相似性低于65%,表明粗饲料种类影响梅花鹿瘤胃细菌区系。OL组梅花鹿A和B的DGGE图谱相似度大于70%,CS组梅花鹿C和D的DGGE图谱相似性大于75%,而且同组不同个体之间瘤胃细菌区系存在差异。OL组和CS组分别获得20和24个DGGE特异性条带。序列分析表明,CS组条带可归类为拟杆菌门、厚壁菌门和变形菌门,而OL组条带可归类为拟杆菌门、厚壁菌门、变形菌门和互养菌门。OL组与CS组中存在大量Prevotella spp.,但不同组中Prevotella spp.在种水平组成不同,主要纤维降解菌为Clostridium spp.与Eubacterium spp.。T-RFLP结果显示,梅花鹿D（CS组）具有最高的丰富度、多样性、均匀度和最低的优势度,梅花鹿A和B的各项指数相近但低于梅花鹿D,说明OL组中的粗饲料（柞树叶）影响瘤胃中微生物的相对生物量。梅花鹿C和D的各项指数相差较大而且梅花鹿C的指数低于梅花鹿A和B,表明同组不同个体之间存在差异。81、214、272和308 bp的T-RFs为OL组优势条带,90、95、175、273和274 bp的T-RFs为CS组优势条带,161、259、264、266和284 bp的T-RFs为共同条带。根据MiCAⅢ结果,这些T-RFs代表细菌归类于拟杆菌门、厚壁菌门、变形菌门和酸杆菌门。T-RFs图谱聚类表明,4头梅花鹿T-RFs聚为两类,粗饲料来源影响梅花鹿瘤胃细菌T-RFs图谱特征,其中梅花鹿A、B和C的T-RFs特征条带图谱相似。【结论】Prevotella spp.是梅花鹿瘤胃优势细菌,但不同粗饲料影响梅花鹿瘤胃细菌区系组成。     

马尾松瘤锈病与酚类物质关系的研究

对马尾松瘤锈病，健组织中酚类物质含量进行了生化分析，结果表明，病瘤木质部中总酚和缩合单宁含量均高于病树其它部位和健树木质部，距瘤越远酚类含量越低，病瘤韧皮部中，总酚和缩合单宁含量也明显高于对病树其它部位韧皮部，马尾松被瘤锈病菌侵染后，树干组织中酚类物质含量发生了变化，病组织总酚和缩合单宁含量均高于健康组织。     

Storage time and condensed tannin content of high-moisture sorghum grains: Effects on in vitro fermentation and mold populations

Silage of high moisture sorghum grains is a highly relevant source of energy in cattle production systems in South America. There is little information related to the chemical characteristics, the kinetics of fermentation and the toxic fungal populations of these feedstuffs. The aim of this study was to evaluate the effect of storage time and condensed tannins content of the grain on chemical composition, in vitro fermentation parameters, and toxicogenic fungal populations of moist sorghum grain stored in silo-bags. Samples of 2 varieties of sorghum grains (high-tannin [HT] and low-tannin [LT]), were obtained during the grain harvest before silage making and after 30, 90, and 180 d of storage (n = 16). High-tannin grains had higher acid detergent fiber, tannins, gas production (P < 0.05) and lower starch and rate of gas production (P < 0.01). Interaction variety × storage time were observed for all chemical parameters (P < 0.01), except for neutral detergent fiber assayed with a heat stable amylase and expressed inclusive of residual ash (aNDF) and pH. Starch and protein content increased in both varieties, tannins decreased in HT and LT, and organic matter (OM) increased in HT and declined in LT (P < 0.05). The rate of gas production increased with the storage time for HT and LT (P < 0.01). A linear reduction in the Aspergillus number of colonies in the HT varieties was observed (P < 0.01), whereas a linear increase in Penicillium isolation was detected in the LT sorghums (P < 0.01). The storage time was beneficial in terms of decreasing the condensed tannins, increasing fractional rate of gas production and minimizing fungal contamination, particularly on HT grains.     

Sorghum and millet phenols and antioxidants

Sorghum is a good source of phenolic compounds with a variety of genetically dependent types and levels including phenolic acids, flavonoids, and condensed tannins. Most sorghums do not contain condensed tannins, but all contain phenolic acids. Pigmented sorghums contain unique anthocyanins that could be potential food colorants. Some sorghums have a prominent pigmented testa that contains condensed tannins composed of flavan-3-ols with variable length. Flavan-3-ols of up to 8–10 units have been separated and quantitatively analyzed. These tannin sorghums are excellent antioxidants, which slow hydrolysis in foods, produce naturally dark-colored products and increase the dietary fiber levels of food products. Sorghums have high concentration of 3-deoxyanthocyanins (i.e. luteolinidin and apigenidin) that give stable pigments at high pH. Pigmented and tannin sorghum varieties have high antioxidant levels that are comparable to fruits and vegetables. Finger millet has tannins in some varieties that contain a red testa. There are limited data on the phenolic compounds in millets; only phenolic acids and flavones have been identified.     

In vitro enzymatic hydrolysis of protein and protein pattern change of soya and faba beans during germination

In addition to technological processes like heat treatment, germination can be an alternative process for the improvement of protein quality of legumes. This was demonstrated by enzymatic protein hydrolysis of flour of germinated faba and soya beans, using a pepsinpancreatin enzyme system. SDS-PAGE was used to study the changes in protein pattern of these legumes during germination. In addition, the effect of germination on the content of condensed tannins in flour from germinated faba beans and trypsin inhibitors in flour from germinated soya beans were studied. Germination for five days resulted in a maximum increase in enzymatic protein hydrolysis by 21.3% in flour from faba beans and by 25.7% in flour from soya beans after 12 hours of germination. Protein patterns, obtained with SDS-PAGE demonstrated a considerable protein breakdown during germination between day 2 and 3 in faba beans and between day 1 and 2 in soya beans. The tannin content in flour from faba beans decreased by 29.7% after seven days of germination, but the tannin content of the hulls of the faba beans did not change during that period of germination. The trypsin inhibitors in flour from soya beans decreased by 25.5% after seven days of germination. We conclude that the increased enzymatic hydrolysis of protein in both legumes cannot be explained by a decrease of tannins or trypsin inhibitors. The possible explanation is that through degradation of proteins during germination of the legumes, the cleaved protein fragments are more susceptable for hydrolysis by pepsin-pancreatin.     

The presence and inactivation of trypsin inhibitors,tannins, lectins and amylase inhibitors in legume seeds during germination. A review

During the germination of legume seeds, enzymes become active in order to degrade starch, storage-protein and proteinaceous antinutritional factors. The degradation of storage-protein is necessary to make peptides and amino acids available in order to stimulate seed growth and early plant growth. Proteinaceous antinutritional factors such as amylase inhibitors, lectins and trypsin inhibitors are present in legume seeds and protect them against predators. However, during germination, they degrade to a lower level by the action of several enzymes. The effect of germination on the content and activity of amylase inhibitors, lectins, tannins and trypsin inhibitors is discussed.     

Tree species-mediated spatial patchiness of the composition of microbial community and physicochemical properties in the topsoils of a tropical montane forest

To evaluate the importance of plant-soil feedbacks in forest ecosystems, it is fundamental to understand the spatial range within which plant species control soil physicochemical and microbial properties. We investigated the spatial pattern of soil properties associated with canopy trees in a tropical montane forest on Mt. Kianbalu, Borneo. We analyzed soil physicochemical properties and microbial communities (biomarker lipid abundance) as a function of soil depth and distance from the tree trunk of a conifer (Dacrydium gracilis) or a broadleaf tree (Lithocarpus clementianus). The concentration of condensed tannins and fungi-to-bacteria were higher beneath Dacrydium than beneath Lithocarpus. Furthermore, carbon-degrading enzyme activities were lower beneath Dacrydium. These effects of the tree species were more distinct on soil properties beneath the tree crown than on those outside the tree crown. These effects appeared to be largely due to differences in litter chemistry, and the distinct set of soil properties formed corresponding to the above canopy crown. In conclusion, the species-rich forest on the tropical mountain contains spatially distinct units of soil properties associated with canopy trees, and this spatial pattern can influence ecosystem dynamics in the forest through plant-soil feedback effects.     

Caution against Determining Tannins in Soil using the Protein Precipitable Phenolics Assay

The aim of this study was to assess the use of the protein precipitable phenolics assay as a method for estimating tannin in soil samples. This method is more selective than general methods such as Folin assays and is used to differentiate tannin from other phenolics in plant extracts. We evaluated the role of the protein as an agent that separated tannin from nontannin phenolics in soil by running the assay in the normal mode, with protein present, and in a modified format without the protein. We tested the method using native soils and soils amended with tannic acid. We found that this assay is not suitable for determining tannin in soil samples, because the protein precipitation step is incompatible with solid soil samples. We also assessed the background color of soil samples in the assay and established that background color is so high that reliable absorbance readings cannot be obtained.     

植物缩合单宁对草食动物的抗寄生虫性

植物缩合单宁广泛存在于众多植物种群,具有抵御动物摄食的化学防卫功能.近年来植物缩合单宁因其抗寄生虫性受到愈来愈多的关注,相关研究为动物肠胃道寄生虫防控提供了新的途径,它有望成为传统化学驱虫剂的替代物质.本文在总结了迄今研究成果的基础上,将植物缩合单宁的抗寄生虫机制归纳为营养免疫假说和代谢阻断假说,并详细阐述了影响植物缩合单宁抗寄生虫性的各种因素.