Organic acids in root exudates from Picea abies seedlings influenced by mycorrhiza and aluminum

Organic acid anions exuded from roots of Picea abies (Norway spruce) seedlings grown on glass beads in the presence and absence of mycorrhiza (Laccaria bicolor) and aluminum (Al) at pH 3.9 were measured. We wanted to test if the roots exuded more organic acid anions when exposed to Al and if mycorrhization influenced the exudation. Oxalate was exuded in far higher amounts than any other organic acid anion, with a maximum rate of 1.7 nmol (mg root DW)^–1 d^–1. Mycorrhizal roots exuded significantly more oxalate than nonmycorrhizal roots. The presence of Al did not enhance oxalate exudation. We conclude that the oxalate exuded constitutively by Picea abies/Laccaria bicolor may lead to rhizosphere oxalate concentrations that are relevant for Al resistance.     

哲罗鱼基因组微卫星富集文库的构建与分析

采用磁珠富集法构建哲罗鱼（Hucho taimen Pallas）荩因组微卫星文库。哲罗鱼基因组DNA经MboⅠ限制性内切酶消化后，选取400-900bp的片段，用生物素标记的简单重复序列（ACA）15作探针与其杂交，杂交复合物结合到包被有链霉亲和素的磁珠上，获得目的片段，连接T载体克隆，构建基因组微卫旱富集文库。再用同位素标记的（ACA）15探针进行二次筛选，筛选出686个阳性克隆，阳性克隆率为35．94％。对其中140个阳性克隆进行测序，共获得149个微卫星序列，4个小卫星序列，其GenBank Accession Number为DQ110955～DQ121108。其中perfect（完美型）62个，占41．61％；imperfect（非完美型）92个，占61．74％；compound（混合型）5个，占3．36％，重复次数主要分布于6～45（81．21％），平均重复次数为32．5，这表明（ACA／TGT）。在哲罗鱼基因组DNA中含最非常丰富。本研究旨为从DNA水平上研究哲岁鱼种群结构、遗传多样性及目前群体现状等方面提供有效工具。     

珠颈斑鸠繁殖生态观察

2006～2007年的1～12月，对山西芦芽山自然保护区内珠颈斑鸠的繁殖生态和种群数量进行了观察。在该区珠颈斑鸠年繁殖1次，巢多营建于小树枝杈、或岩石洞穴中，有利用旧巢的习性，窝卵数多为2枚，卵重平均15.67（15.0～16.4）g。雌雄鸟均参加孵卵，孵化期18d，孵化率100%，离巢率87.5%，巢内育雏17～19d，种群密度为15.79只/km。     

Performance of zein-bound particles for delivery of riboflavin to early fish larvae

Zein‐bound particles (ZBP), complex particles (CP) and lipid spray beads (LSB) were prepared and their performances were compared for delivering riboflavin to early fish larvae. Measures of performances of microparticles included inclusion, encapsulation, retention and delivery efficiencies in addition to T₅₀ (time to 50% retention) values. ZBP were not efficient in retaining riboflavin. Maximum retention (RE) and delivery (DE) efficiencies for riboflavin incorporated in ZBP occurred with 12.5% w/w lipid added to the particles. Substitution of menhaden oil with higher melting point lipids did not have any effect on retention of riboflavin. ZBP prepared by a spray‐dry method had higher RE and DE compared with those of ZBP prepared by freeze‐dry and spray‐water methods. Elimination of water from the manufacture process resulted in significantly higher inclusion and encapsulation efficiencies of ZBP but did not affect retention rates. CP containing LSB and a dietary mixture bound together with zein had significantly higher retention and delivery efficiencies for riboflavin compared with those of ZBP. Fifty per cent of the initial riboflavin in CP was retained after 75 min of suspension in water. Although free LSB had higher retention efficiencies for riboflavin compared with CP, free LSB clumped and floated when suspended in water and were unavailable to fish larvae. Therefore, LSB should be incorporated into CP for more effective delivery of water‐soluble nutrients in larval fish nutrition studies.     

Comparison of lipid-walled microcapsules and lipid spray beads for the delivery of water-soluble, low-molecular-weight materials to aquatic animals

Microparticles (< 40 μm diameter) composed of 600 mg g⁻¹ tripalmitin/400 mg g⁻¹ fish oil were used to encapsulate the low-molecular-weight (mol. wt 460) antibiotic oxytetracycline in the form of either oxytetracycline hydrochloride (OTC.HCl) or oxytetracycline hemicalcium salt (OTC.HEM). Dry, finely ground particles of core material were encapsulated in spray beads. Dissolved core material was encapsulated in lipid-walled microcapsules.
Oxytetracycline (OTC) was most efficiently delivered (≈ 46.5 mg g⁻¹ lipid after 24 h suspension in seawater) as a hemicalcium salt in spray beads. Lipid-walled microcapsules were most efficient for delivering OTC (≈ 8.7 mg g⁻¹ lipid) as OTC.HCl dissolved in 0.2  M HCl at a concentration of 300 mg mL⁻¹.
Spray beads containing OTC.HEM were very stable over 1 month in storage. Lipid-walled microcapsules containing aqueous OTC.HCl lost ≈ 30% of their core material during storage. Freeze-drying of both microparticle types did not improve storage of spray beads, but showed promise for reducing leakage from lipid-walled microcapsules during storage and delivery to suspension feeders.     

李斯特氏菌因子血清的制备及食品检测的免疫磁性分离-PCR(MIPA)方法的建立

首先进行了李斯特氏菌因子血清的研制，制备出了可对所有李斯特氏菌分型的 １５ 个 Ｏ 抗原因子和４ 个 Ｈ 抗原因子的因子血清。利用复合因子血清的多克隆抗体包被磁性球，对食品中的单核细胞增多性李斯特氏菌进行免疫磁性分离，并与 Ｐ Ｃ Ｒ 方法相结合，建立了检测食品中单核细胞增多性李斯特氏菌的 Ｍ Ｉ Ｐ Ａ方法（免疫磁性分离—聚合酶链反应方法，ｍ ａｇｎ ｅｔｉｃ ｉｍ ｍ ｕｎｏｐｏｌｙｍ ｅｒａｓｅ ｃｈａｉｎ ｒｅａｃｔｉｏｎ ａｓｓａｙ）。对菌液、模拟样品的检测表明，本方法能够有效地克服食品基质、培养基成分和杂菌对 Ｐ Ｃ Ｒ 检验的干扰作用。食品样品在 Ｅ Ｂ增菌液中增菌 １２ ｈ 后，检测的敏感度达 ５ Ｃ Ｆ Ｕ／ｍ Ｌ，可以在 ２０ ｈ 内完成检测。本方法对实际食品样品的检测结果，与国家标准检验方法检测的结果一致。     

鸭微卫星标记的筛选及其遗传多样性分析

采用磁珠富集法从AFLP片段中筛选微卫星标记,并对5个福建地方鸭品种的遗传多样性进行检测。基因组DNA用EcoRⅠ/MseⅠ内切酶酶切的同时与接头连接,酶切连接产物与用生物素标记的探针杂交,应用磁珠捕获100~2000bp含有微卫星序列的DNA片段并通过pGEM-T载体转化到大肠杆菌DH5a感受态细胞中,构建富集微卫星序列的基因组文库。随机挑选46个阳性克隆,测序获得14条含有微卫星的DNA序列并递交到GenBank（登录号：FJ599499~FJ599512）。设计合成14对微卫星引物,通过PCR优化从中选择5对引物用于5个福建地方鸭品种的遗传多样性分析。结果显示,5对微卫星引物共检测到31个等位基因,各微卫星基因座的有效等位基因数为1.969 7~2.834 4,多态信息含量和杂合度的平均值分别为0.5133和0.7480,遗传多样性丰富,说明磁珠富集法适合用于鸭微卫星标记的分离与筛选,筛选得到的5个微卫星位点可作为有效的遗传标记用于福建省地方鸭品种遗传多样性的研究。     

磁珠富集法分离草鱼微卫星分子标记

磁珠富集法是一种快速、高效的分离微卫星分子标记的方法。本研究通过该方法分离草鱼的微卫星分子标记。将草鱼（Ctenopharyngodon idella）基因组DNA经Sau3AI酶切，同收纯化400～900bp片段，连上接头，构建“基因组PCR文库”。用生物素标记的简单重复序列（CA）15作探针与其杂交，杂交复合物结合到包被有链霉亲和素的磁珠上，经一系列的洗涤过程，去除磁珠表面不含有微卫星的片段。将吸附在磁珠上的片段洗脱，PCR扩增放大，再进行克隆和测序，根据微卫星两端的保守序列设计引物，即可得到微卫星分子标记。本研究义通过同位素标记的探针（CA）15进行二次杂交筛选，获得阳性克隆132个，所得到的阳性克隆经测序，86．36％含有微卫星序列，共获得130个微卫星DNA序列。用引物设计软件Primer Premier5．0没计引物83对。     

ISSR-PCR和链亲和素磁珠吸附法开发白菜SSR引物

  分别利用ISSR-PCR和链亲和素磁珠吸附法分离白菜基因组微卫星, 共得到41对SSR引物。ISSR-PCR法运用巢式PCR, 分别设计微卫星两侧引物IP₂ 和IP₃ , SSR引物得率为12%。磁珠吸附法首先利用生物素标记的SSR探针与文库杂交, 链亲和素磁珠吸附富集含SSR的片段。然后用接头引物扩增, 克隆。根据测序结果, 设计SSR两侧引物PL 和PR, 引物得率为9.6%。     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.