几种胡敏酸还原容量的表征与比较

还原容量(RC)是衡量胡敏酸(HA)还原特性的重要指标。采用饱和H2振荡法和土壤溶液法对HA分别进行化学和微生物预处理,分别以硝酸铁(Fe(NO3)3)、柠檬酸铁(FeCit)作电子受体,测定了三种HA(上海巨枫SH,天津光复TJ,缙云山JY)的本底还原容量(NRC),化学还原容量(CRC),微生物还原容量(MRC)。对不同电子受体条件下、不同初始状态和不同种类的胡敏酸的RC进行比较。结果表明：三种HA中,以缙云山土壤提取的胡敏酸RC值最高,还原容量最大,分别为20.21?0.26mmolc mol-1C (NRC)、26.02?1.12mmolc mol-1C (CRC)和29.29?1.56mmolc mol-1C (MRC)。两种电子受体中,采用Fe(NO3)3得到的RC明显高于在FeCit条件下。另外,溶液态HA的RC明显高于固态。由此证明胡敏酸还原容量是一个相对量;其容量大小不仅和自身结构、性质有关,也受到HA初始形态和不同电子受体的影响。对比三个还原容量指标发现CRC和MRC显著大于NRC,而CRC和MRC之间无明确大小关系,因此用CRC来表征HA被微生物还原后的还原容量(MRC)还需作进一步验证。     

Proteome response of Monascus pilosus during rice starch limitation with suppression of monascorubramine production

For centuries, red mold rice has been made by fermentation of cooked rice with Monascus species. However, the influence of different carbon sources on the metabolism of Monascus cells remains unclear. We compared the proteome response of Monascus pilosus to replacement of the rice starch fraction with lactose during cultivation, using two-dimensional gel electrophoresis, matrix-assisted laser desorption-ionization time-of-flight/time-of-flight mass spectrometry, and tandem mass spectrometry to identify the proteins expressed. The results showed that cell growth and monascorubramine pigment formation of M. pilosus were sensitive to rice starch limitation during cultivation. A total of 12 proteins were identified with statistically altered expression in the cells cultivated with lactose. These deregulated proteins were involved in glycolysis, TCA cycle, energy generation, protein folding, and peptide biosynthesis. The possible metabolic flux shifts induced by rice starch limitation were discussed. The results suggested that the suppression of monascorubramine formation could be related to the necessary energy-requiring adaptations executed in response to carbon depletion during rice starch limitation.     

模拟干旱胁迫下不同甘蓝型油菜品种发芽能力的配合力与遗传效应分析

选择7个干旱胁迫下发芽能力不同的甘蓝型油菜品种进行完全双列杂交, 将亲本及F₁代种子在10% PEG模拟干旱胁迫条件下发芽, 测定相对单株鲜重、相对茎长、相对成苗率、相对发芽率、相对发芽势和相对活力指数, 用Griffing I方法对发芽性状进行一般配合力(GCA)和特殊配合力(SCA)遗传分析。结果表明, 一般配合力方差在42个组合间各性状达到了极显著水平, 特殊配合力方差在42个组合间除了相对活力指数外的各性状也达到了极显著水平。其中, 中双9号上述6性状的一般配合力效应值最高分别为0.0656、0.0708、0.1185、0.1048、0.1096和0.0861; 中双6号一般配合力效应虽然不高, 但其组合中双6号×西农长角和中双6号×中双10号的特殊配合力效应较高, 是耐旱性较强的组合。     

棉花RGAP、DGAP和DDRT标记的定位研究

 根据本实验室已克隆的RGAs和DGAs,设计48条RGAs和4条DGAs特异引物,以“海7124×TM-1”组合的BC₁群体为材料把5个RGAP和2个DGAP标记定位到棉花的染色体上;以一个高抗黄萎病陆地棉品系5026为材料,在接种黄萎病菌后不同时期提取根部RNA,用mRNA差异显示（DDRT-PCR）技术,获得164个差异片段,根据这些片段设计34对DDRT引物。用已构建好的“海7124×军棉1号”组合的F₂群体,将3个RGAP和5个DDRT定位到了相应的染色体上。用Joinmap3.0软件把两张连锁图谱整合为一张图谱,并将这些标记与抗黄萎病QTLs进行连锁分析。     

小麦抗白粉病基因来源及抗性评价的研究进展

小麦白粉病是小麦生产的主要病害之一,应用抗病品种是防治该病十分经济、有效的措施。目前为止,小麦基因组中有41个位点的56个抗白粉病基因被标记和作图。本文详细叙述了小麦抗白粉病基因的来源及抗病基因利用,旨在为我国抗小麦白粉病分子育种提供参考。     

螺旋式胡椒鲜果脱皮机的设计与试验分析

为解决现有胡椒鲜果脱皮机脱皮不彻底导致含杂率高、脱皮力不当导致果核破碎及果核保护膜破损导致白胡椒色泽不理想等问题,在分析现有胡椒机械加工工艺的基础上,研制出螺旋式胡椒鲜果脱皮机。该机通过螺旋网面挤压胡椒鲜果,胡椒鲜果表皮在螺旋网面及容器内壁发生摩擦作用以完成脱皮。试验结果表明:螺旋式胡椒鲜果脱皮机的脱皮率达93%以上,且果核损伤率低于3%,符合设计要求。     

并联式球面变胞机构及其完整雅可比矩阵

提出了一种球面变胞机构。该机构采用并联连接方式,由动平台、静平台、3个环形支链和1个中间变胞支链组成,通过变胞支链提供不同约束,机构可演变为正常构态和变胞构态两种机构形式。正常构态时,动平台相对静平台具有3个转动自由度,等效于3自由度球面机构;变胞构态时,动平台具有一个额外的径向移动自由度。以螺旋理论为基础,首先分析机构的自由度数目和性质;其次,构建机构的运动子矩阵和约束子矩阵,并将约束子矩阵和运动子矩阵联立,建立完整的6×6雅可比矩阵;最后,分析雅可比矩阵的秩,得到机构产生奇异位形的条件,研究奇异位形的类型,提出避免发生奇异的方法,为机构设计提供理论依据。     

Flavonoid constituents of Chorizanthe diffusa with potential cancer chemopreventive activity

An ethyl acetate-soluble extract of Chorizanthe diffusa was found to exhibit significant antioxidant activity, as judged by scavenging stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals and inhibition of 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced free radical formation with cultured HL-60 cells. Bioassay-directed fractionation of this extract using the DPPH antioxidant assay as a monitor led to the isolation of five structurally related flavonoids (1-5), including the novel compound 5,8,3',4',5'-pentahydroxy-3, 7-dimethoxyflavone (1). Isolates 1-5 demonstrated varying degrees of antioxidant or antimutagenic activity. Two of the compounds, 5,7,3', 4'-tetrahydroxy-3-methoxyflavone (2) and quercetin (4), were subsequently found to inhibit carcinogen-induced preneoplastic lesions in a mouse mammary organ culture model. Inhibitory activity of this type is known to correlate with cancer chemopreventive effects in full-term models of tumorigenesis.     

发酵糟渣旋流闪蒸干燥及其热物性参数的快速测定

介绍了利用旋流闪蒸干燥器干燥发酵糟渣时，气流与物料间放热系数及糟渣物料热传导率、热扩散系数的简便快速测定方法。     

Tillage and crop sequence effects on organic carbon and total nitrogen content in an irrigated Alberta soil

A better understanding of tillage effects on soil organic matter is vital for development of effective soil conservation practices. The objective of this research is to determine the effect of tillage and crop sequence on soil organic carbon (OC) and total nitrogen (TN) content in an irrigated southern Alberta soil. A field experiment was conducted using a split–split plot design from 1994 to 1998 in Alberta, Canada. There were two crop sequences (Sequence 1: spring wheat (Triticum aestivum L.)–sugar beet (Beta vulgaris L.)–spring wheat–annual legume; and Sequence 2: spring wheat–spring wheat–annual legume–sugar beet) and two tillage practices (CT: conventional tillage and MT: minimum tillage). Surface soil under MT had significantly higher OC (30.1 Mg ha⁻¹) content than under CT (28.3 Mg ha⁻¹) after 4 years of treatment. The MT treatment retains crop residue at the soil surface, reduces soil erosion and slows organic matter decomposition, which are key factors in enhancing the soil fertility status of southern Alberta irrigated soils.