单核细胞增生李斯特菌 sRNA 伴侣分子 hfq的基因克隆、表达及纯化

为克隆、表达单核细胞增生李斯特菌sRNA分子伴侣蛋白hfq基因,并纯化重组蛋白,通过PCR的方法从单核细胞增生李斯特菌基因组DNA中扩增出hfq基因,将扩增产物克隆于pMD18-T载体中,测序验证后,再将hfq基因亚克隆至表达载体pET-32a（＋）中,成功构建pET-32a（＋）-hfq原核表达载体。然后,转化至大肠杆菌BL21（DE3）感受态细胞中,通过IPTG进行诱导表达,对表达蛋白进行可溶性分析,并采用Ni-NTA纯化目的蛋白。结果显示：克隆的hfq基因全长234 bp,编码77个氨基酸,通过SDS-PAGE可以检测到27 kDa的蛋白特异性条带;并从上清中纯化得到了Hfq融合蛋白。为进一步研究该蛋白的生物学功能奠定了基础。     

浅圆仓不同功率风机通风试验研究

利用2.2kW的轴流风机组与7.5kW的离心风机组,对两个浅圆仓进行通风降温,经对比试验,在储粮数量、储粮品种、入仓时间、入仓质量、粮情状况等基本相同的浅圆仓中,当降温效果基本相同时,2.2kW的轴流风机组通风时间较长,7.5kW离心风机组降温效果较快,但水损较多,2.2kW的轴流风机组通风耗能较低,吨粮降温成本较低。     

针形名茶“永川秀芽”自动揉捻工艺的研究

采用6CRK—40自动揉捻机,以不同品种原料和初揉、复揉工艺为试验因素,进行3因素3水平正交试验,比较分析其对揉捻叶、成品茶、内含成分的影响。结果表明,川茶等小叶种原料自动揉捻工艺组合为Z1+F1号工艺;福鼎等中叶种原料自动揉捻工艺组合为Z2+F3号工艺;蜀永2号等大叶种原料自动揉捻工艺组合为Z1+F3号工艺。     

直剪法用于糙米内摩擦角的测定与研究

利用土工合成材料综合测定仪（直剪仪）,以水分含量14.57%的糙米为样品,测定了在不同的法向压应力、不同的剪切速率下糙米的剪切应力并计算出内摩擦角。实验结果表明：糙米的剪切应力随着法向压应力（25kPa～100kPa）的增大而增大;剪切速率（1.33mm/min～2.67mm/min）较低时糙米的内摩擦角随着法向压应力的增大而减小;随着剪切速率（1.33mm/min～5.20mm/min）的增大,糙米的内摩擦角减小。     

微生物预处理秸秆纤维浆结构、形态及成膜性研究

为研究生物预处理对秸秆纤维解离作用,促进制浆过程纤维分丝帚化及成膜性,采用实验室模拟发酵法,探讨微生物接种量及发酵时间对秸秆纤维化学组分、纤维形态及膜力学性质的影响。结果表明,与对照相比,接种1%外源菌处理稻秸14天时降解率达到20%,纤维降解适中,细小纤维占比仅59.63%~67.91%,纤维间交织力增强,纤维的疏解与拆分效应提升,打浆能耗降低71.54%。且随发酵时间的延长,纤维膜的抗张强度先升高再降低,第7和14天时分别提高7.6%和4.64%;3%接菌量处理14天时,浆料重均和质量加权增幅最大至28.57%和49.36%,膜撕裂度最高达240.9 mN。抗张强度与纤维质量间无明显相关性,耐破强度与纤维质量加权长度间呈负相关,撕裂强度与纤维数均长度、重均及纤维长宽比间呈显著正相关。该研究为生物降解秸秆纤维地膜的开发应用可行性提供技术支撑。     

改革开放以来广东农民收入变化特征及未来选择

农业农村工作,说一千、道一万,增加农民收入是关键.本文通过系统回顾改革开放40多年来广东农民收入的变动历程及其来源构成,分析当前及今后一段时期广东农民增收面临的主要问题和挑战,判断未来广东农民收入的增长点及政策选择,具有重要现实意义.研究发现,改革开放以来广东农民收入增速经历了"快速增长—明显下滑—恢复—低迷—持续较快...     

Isolation of a new repetitive DNA sequence from Secale africanum enables targeting of Secale chromatin in wheat background

A genome specific DNA sequence that detects Secale africanum chromatin incorporated into wheat was developed in this study. Random amplified polymorphic DNA (RAPD) analysis was used to search for genome specific DNA sequences of S. africanum in lines, R111, “mianyang11” (MY11) and wheat-rye 1RS/1BL translocations R25 and R57. A high copy rye-specific DNA segment pSaD15₉₄₀ of the S. africanum genome was obtained. The sequence of pSaD15 did not show any significant homology to other reported sequences in databases and it is therefore a new repetitive sequence of Secale. PCR primers were designed for pSaD15₉₄₀, which amplify a clear 887 bp fragment in S. africanum but not in any wheat. The primers also amplified an 887 bp fragment in other accessions of rye, Chinese Spring-Imperial rye chromosome additions and a diverse range of material carrying different rye chromosomes or chromosomal segments. In situ hybridization showed that probe pSaD15₉₄₀ was specifically hybridized throughout all rye chromosomes arms except for the terminal regions. The advantage of the rye-specific probe developed herein compared to those of previous reports is that it has been shown to be widely applicable to other Secale species. The probe will be useful as a molecular marker for the introgression of S. africanum and other rye chromosome segments into the wheat genome.     

Genetic analysis of a novel dominant rice dwarf mutant 986083D

This study was to determine the agronomic and genetic characteristics of a novel rice dominant dwarf mutant 986083D (japonica) and its potential in breeding. 986083D derived from the anther culture of an autotetraploid indica/japonica hybrid and its progeny segregated into normal and dwarf plants. Homozygous and heterozygous 986083D plants looked similar phenotypically, showing shortened stature, erect leaves, more tillers and poor fertility. The segregation ratio of dwarf to normal plants fit the expected 3:1 by χ²-test in 77 out of 88 tested lines. Crosses between homozygous 986083D and eight other rice varieties had uniform semi-dwarf F₁ plants. The F₁ plants from crosses between heterozygous 986083D and five other varieties had normal and semi-dwarf plants close to the expected ratio of 1:1. The reduction of plant height in F₁ plants ranged from 40.0 to 53.5% in a subtropical environment and from 37.5 to 48.2% in a temperate environment. 986083D showed moderate sensitivity to exogenously applied GA₃ in terms of elongation of shoots and induction of α-amylase activity in the endosperm. Linkage analysis showed that the dominant dwarf gene (designated as Dx) in 986083D was not allelic to D53. Dx was roughly mapped to the short arm of chromosome 8. All results showed that 986083D was a novel mutant controlled by single dominant gene, providing a valuable material in rice breeding. Ruizhen Qin, Yang Qiu contributed equally to this work.     

饥饿对鲫鱼血液生理生化指标和流变学性质的影响

研究了饥饿对鲫鱼血液生理生化指标和流变学性质的影响.于21±1℃条件下,在室内水族箱内对鲫鱼进行了为期28d的饥饿实验,分别在饥饿开始后的0、7、14、21、28d取样并测定了其血液生理生化指标和全血粘度.结果表明血液中红细胞数和红细胞压积分别在饥饿后7d和14d内显著下降,而白细胞数和红细胞沉降率分别在饥饿后7d和21d内显著上升;鲫鱼血清中的血糖对饥饿特别敏感,在饥饿后7d内明显下降(P＜0.05),此后几周变化不明显(P＞0.05);总蛋白和白蛋白在饥饿后7d内均有所增加,然后下降;谷丙转氨酶活性在饥饿后14d内明显下降,甘油三脂和总胆固醇在饥饿后21d内明显下降;饥饿对鲫鱼血清钙离子浓度和碱性磷酸酶活性没有显著性影响.全血粘度值在饥饿后14d内下降,随后全血粘度值逐渐增加,到饥饿后28d时仍低于正常值.结果提示,饥饿对鲫鱼大部分血液生理生化指标和血液流变学性质有显著性影响.     

不同水稻品种在Cd、As和Hg胁迫下的吸收积累特性

为筛选籽粒中Cd、As和Hg低吸收或低积累的品种或育种中间材料,采用人工添加 Cd(CdCl2·2.5H2O)、As(NaAsO2)和 Hg[Hg(NO3)2·0.5H2O]等重金属化合物的方法污粢土壤,研究不同水稻品种对Cd、As 和 Hg 胁迫的吸收积累特性.结果表明,Cd、As 和 Hg 胁迫时,水稻茎叶、稻谷和精米中均会增加相应重金属的含量;As 和 Hg 主要在茎叶中积累,而籽粒中的含量较低;精米中 Cd 的含量与稻谷和茎叶中的含量差异较小.茎叶中 Cd、As 和Hg 的含量显著或极显著高于稻谷和精米,而精米中相应重金属的含量与稻谷中含量的差异均不显著.南粳 41、金陵香糯、武育粳3号、华粳3号、02428、龙睛4号和云南新团黑谷等7个品种精米中Cd和As的含量均达到绿色食品大米标准;所有品种精米中Hg的含量均未达到无公害食品大米标准.