麦类作物种子中戊聚糖研究进展

戊聚糖是谷物种子中,特别是小麦种子中重要的非淀粉多糖,也是麦类面粉的重要功能性成分,对面包品质有重要影响。由于戊聚糖在面包工业和保健品行业具有广阔的应用前景,近50年来,国外对其开展了较为系统和深入的研究。本文回顾了近年来有关戊聚糖的最新研究进展,包括其组成、结构、含量及其测定方法以及在面包烘焙中的应用等。     

小麦籽粒中植酸、戊聚糖含量及其与相关性状关系的研究

选用不同基因型小麦,测定了籽粒中植酸、蛋白质及戊聚糖的含量,并对其进行遗传相关分析,结果表明：(1)各性状在品种间存在显著性差异,且植酸的广义遗传力比较低;(2)植酸含量与蛋白质含量呈极显著的正相关,与戊聚糖呈极显著负相关。通过对参试的18个不同基因型小麦中植酸和戊聚糖含量进行聚类分析,可以将18个基因型小麦聚为四类,并初步认为豫麦47是参试品种中最适宜于用作饲用小麦。     

河南若干小麦品种籽粒戊聚糖含量的初步研究

1999-2000年对河南省8个有代表性的小麦品种的戊聚糖进行了测定,不同品种戊聚糖的平均含量变化范围为6%-9%。不同品种和不同生态条件下小麦籽粒戊聚糖含量均有很大差异。5个试点小麦籽粒戊聚糖的平均含量与千粒重,降落值均成负相关关系（r=-0.83,r=-0.31),而与蛋白质的含量却呈正相关关系（r=0.35)。说明戊聚糖含量与生态因素有很大关系,采用Eberhart-Russell模型对小鼠戊聚糖含量的稳定性进行分析。发现豫麦34是戊聚糖含量较理想的品种。     

小麦高分子量麦谷蛋白亚基鉴定及其品质效应研究进展

高分子量谷蛋白亚基(HMW-GS,high molecular weight glutenin subunits)是小麦子粒贮藏蛋白的重要组成成分,其组成、搭配、表达水平及含量决定面团弹性和面包加工品质。本文主要介绍了小麦HMW-GS编码基因的克隆、分子特征、分子标记开发及其在小麦育种中的应用,并综述了不同HMW-GS与面粉加工品质之间的关系,以及HMW-GS基因遗传转化、微量配粉和突变体培育等方面的研究进展,分析了目前研究中存在的主要问题,认为通过分子标记辅助选择和转基因技术聚合优质亚基,培育优质面包小麦品种和明确各个HMW-GS基因的品质效应是今后的研究重点。     

小麦等谷类植物种子贮藏蛋白基因的表达与调控

高等植物在成熟期的主要生理过程是将蛋白质、淀粉和脂肪等贮藏在种子中。贮藏在种子中的蛋白质称为种子贮藏蛋白。小麦、水稻、玉米等粮食作物是人类和家畜摄取蛋白质的重要来源。研究贮藏蛋白基因在种子发育过程中的表达机制,是进一步应用生物技术改良作物的基础工作。1谷物     

细胞分裂素调控种子发育、休眠与萌发的研究进展

种子萌发是子代植株建立、生长和繁育的重要阶段,在种子植物生命周期中起重要作用。种子休眠是在发育过程中形成的,在生理成熟期达到峰值。种子休眠与萌发的植物激素调控可能是种子植物中一种高度保守的机制。细胞分裂素(CK)是植物体内的一种重要信号分子,调控植物生长发育的许多方面。生物活性CK的水平由其生物合成、活化、失活、再活化...     

中国植物种子形态学研究方法和术语

强调了研究中国植物种子形态的重要科学意义和应用价值。介绍了种子形态学研究方法,其内容包括材料选择、形态描述、照相等。解释了常用种子形态学术语,包括种子状果实、种子各组成部分、种子表面及切面、附属物、种皮特化结构、质地等。     

有关植物人工种子研究的初报

人工种子是在离体培养条件下,由单个细胞产生分裂发育成一个胚状体,采用理化因素控制胚状体的同步生长,在胚状体表面包上一层有机化合物做为保护胚状体及提供营养的“种皮”,创造一个和种子相似的结构——人工种子。人工种子具有许多优越性,通过细胞悬浮培养产生的胚状体具有数量多(1升培养基可     

酸面团发酵剂在发酵面食品加工中的研究进展

综述了酸面团的种类、分离培养方法,以及在面包、馒头等发酵面食品加工中的应用研究进展。研究显示,酸面团可以改善面团的延伸性和可塑性等加工性能,提高制品膳食纤维、矿物质、B族维生素的有效性,以及氨基酸、多肽等生物活性物质的含量,是加工无面筋质面包、馒头,以及低糖高膳食纤维的功能性发酵面食品的良好选择。酸面团的特殊菌群提高了面包、馒头的抗霉菌污染性能和保水能力,在延长面包、馒头的货架期方面效果显著。     

葫芦巴香料资源开发及综合利用前景

一、葫芦巴香料国内外利用概况葫芦巴又名香豆子、香草,为豆科一年生草本。原产地中海沿岸,并早已栽培。在西欧、非洲及西南亚洲,它是一种广泛种植的调味品作物;种子含有香豆素,习惯用于汤菜和咖哩食品中。在北非及回民地区,它被混合于作面包的原料中或花卷等食品中作调香料。     

Effects of enzyme supplementation of diets based on wheat, rye or triticale on their productive value for broiler chickens

Iso-nitrogenous and iso-energetic diets based on wheat, rye and 3 triticale cultivars were given with or without a supplement with a technical enzyme preparation containing pentosanase activity. The 10 diets obtained were given to a total of 600 broiler chickens from the age of 1 to 34 days. Considerable variation in chemical composition and productive value of the triticale cvs. was found. The triticale cv. Lasko had a chemical composition which closely resembled that of the wheat (cv. Holme), particularly regarding pentosan content. The rye (cv. Kungs II) and the triticale Sv 8008 had higher pentosan contents, while the triticale WW 31433 was intermediate between the wheat and rye.

At 21 days of age, live weights, feed intakes and feed conversion ratios were influenced by cereal type (P < 0.001), enzyme supplementation (P < 0.001) and the interaction of cereal type and enzyme (P < 0.001). In general, Lasko and WW 31433 (triticales) and wheat supported similar poultry production and were only marginally improved by enzyme supplementation. The rye gave an inferior production which, despite substantial improvement with enzyme supplementation, was still lower than that of wheat. Triticale Sv 8008 gave an intermediate production level which increased to that of the wheat following enzyme supplementation. An adaptation to the diets, particularly those rich in pentosans, was apparent as the chickens grew older and this reduced the beneficial effects of enzyme supplementation; however, statistically significant effects were still observed at 34 days of age.

The results indicate that pentosan content may be a negative indicator for evaluating the productive potential of triticale. It was also evident that supplementation with enzyme preparations high in pentosanase activity can improve the nutritive value of diets based on cereal grains with pentosan-rich endosperm cell walls.     

Wheat straw ethanolysis under subcritical and supercritical conditions

The composition of ethanol extract of wheat straw obtained under subcritical and supercritical conditions has been studied. It was found out that treatment with increased temperature, pressure and prolonged time of extraction leads to increased yield of ethanol soluble products, because of destruction of pentosan, lignin and, partially, cellulose. Delignification and hydrolysis product condensation processes prevailed under treatment with temperatures higher than 200°C.     

The role of pentosan polysulfate in treatment approaches for interstitial cystitis

Studies of the mechanisms and causes of interstitial cystitis (IC) and of the properties of pentosan polysulfate have provided a scientific rationale for using pentosan polysulfate to treat IC. In randomized, double-blind studies, patient and investigator evaluations of pentosan polysulfate in the treatment of IC resulted in favorable assessments of the drug. In addition, IC patients in two out of four randomized, prospective trials improved significantly in most variables with treatment by oral pentosan polysulfate; in the two other studies, the IC patients improved in some domains with pentosan therapy, although not significantly. Importantly, two longer-term, patient-evaluation studies showed that a longer duration of treatment with pentosan polysulfate resulted in greater improvements in patients' response rates and outcomes. The results indicate that treatment should be continued for 6 months or longer in order to show significant improvement. Of particular interest are studies suggesting that a potassium test may possibly predict the response of IC patients to treatment with pentosan polysulfate.     

Genomics in cereals: from genome-wide conserved orthologous set (COS) sequences to candidate genes for trait dissection

Recent updates in comparative genomics among cereals have provided the opportunity to identify conserved orthologous set (COS) DNA sequences for cross-genome map-based cloning of candidate genes underpinning quantitative traits. New tools are described that are applicable to any cereal genome of interest, namely, alignment criterion for orthologous couples identification, as well as the Intron Spanning Marker software to automatically select intron-spanning primer pairs. In order to test the software, it was applied to the bread wheat genome, and 695 COS markers were assigned to 1,535 wheat loci (on average one marker/2.6 cM) based on 827 robust rice–wheat orthologs. Furthermore, 31 of the 695 COS markers were selected to fine map a pentosan viscosity quantitative trait loci (QTL) on wheat chromosome 7A. Among the 31 COS markers, 14 (45%) were polymorphic between the parental lines and 12 were mapped within the QTL confidence interval with one marker every 0.6 cM defining candidate genes among the rice orthologous region.     

Sulfated glycans and elevated temperature stimulate PrP(Sc)-dependent cell-free formation of protease-resistant prion protein

A conformational conversion of the normal, protease- sensitive prion protein (PrP-sen or PrP(C)) to a protease-resistant form (PrP-res or PrP(Sc)) is commonly thought to be required in transmissible spongiform encephalopathies (TSEs). Endogenous sulfated glycosaminoglycans are associated with PrP-res deposits in vivo, suggesting that they may facilitate PrP-res formation. On the other hand, certain exogenous sulfated glycans can profoundly inhibit PrP-res accumulation and serve as prophylactic anti-TSE compounds in vivo. To investigate the seemingly paradoxical effects of sulfated glycans on PrP-res formation, we have assayed their direct effects on PrP conversion under physiologically compatible cell-free conditions. Heparan sulfate and pentosan polysulfate stimulated PrP-res formation. Conversion was stimulated further by increased temperature. Both elevated temperature and pentosan polysulfate promoted interspecies PrP conversion. Circular dichroism spectropolarimetry measurements showed that pentosan polysulfate induced a conformational change in PrP-sen that may potentiate its PrP-res-induced conversion. These results show that certain sulfated glycosaminoglycans can directly affect the PrP conversion reaction. Therefore, depending upon the circumstances, sulfated glycans may be either cofactors or inhibitors of this apparently pathogenic process.     

The effects of autolysis on the structure of chicken calpain II.

Heparin catalyses the inhibition of two key enzymes of blood coagulation, namely Factor Xa and thrombin, by enhancing the antiproteinase activities of plasma antithrombin III and heparin cofactor II. In addition, heparin can directly inhibit the activation of Factor X and prothrombin. The contributions of each of these effects to the anticoagulant activity of heparin have not been delineated. We therefore performed experiments to assess how each of these effects of heparin contributes to its anticoagulant activity by comparing the effects of heparin, pentosan polysulphate and D-Phe-Pro-Arg-CH2Cl on the intrinsic pathway of coagulation. Unlike heparin, pentosan polysulphate catalyses only the inhibition of thrombin by plasma. D-Phe-Pro-Arg-CH2Cl is rapid enough an inhibitor of thrombin so that when added to plasma no complexes of thrombin with its inhibitors are formed, whether or not the plasma also contains heparin. Heparin (0.66 microgram/ml) and pentosan polysulphate (6.6 micrograms/ml) completely inhibited the intrinsic-pathway activation of 125I-prothrombin to 125I-prothrombin fragment 1 + 2 and 125I-thrombin. On the addition of thrombin, a good Factor V activator, to the plasma before each sulphated polysaccharide, the inhibition of prothrombin activation was demonstrable only in the presence of higher concentrations of the sulphated polysaccharide. D-Phe-Pro-Arg-CH2Cl also completely inhibited the intrinsic-pathway activation of prothrombin in normal plasma. The inhibitory effect of D-Phe-Pro-Arg-CH2Cl was reversed if thrombin was added to the plasma before D-Phe-Pro-Arg-CH2Cl. The inhibition of the activation of prothrombin by the three agents was also abolished with longer times with re-added Ca2+. Reversal of the inhibitory effects of heparin and pentosan polysulphate was associated with the accelerated formation of 125I-thrombin-antithrombin III and 125I-thrombin-heparin cofactor complexes respectively. These results suggest that the anticoagulant effects of heparin and pentosan polysulphate are mediated primarily by their ability to inhibit the thrombin-dependent activation of Factor V, thereby inhibiting the formation of prothrombinase complex, the physiological activator of prothrombin.     

Naturwissenschaftliche Aspekte eines diffusiven Strohaufschusses mit verdünnter Alkalilauge

Changes in chemical composition and morphology of wheat straw during a 5-step treatment with delute aqueous sodium hydroxide of increasing (step 1 to 3) and then decreasing (step 4 and 5) NaOH concentration are described varying straw pretreatment, maximum NaOH concentration and total time of contact between straw and lye. These structural changes are correlated to increase in swelling, in-vitro degradability by cellulase and digestibility as revealed by feeding tests with sheep. Results are discussed on the basis of the processes of swelling, delignification and pentosan extraction, and the technological advantages of this multi-step treatment for enhancing the nutritional value of straw are discussed in comparison to a one-step treatment with subsequent lye-removal by pressing.