鸡传染性喉气管炎的研究Ⅱ．鸡传染性喉气管炎病毒某些生物学特性的研究

对鸡传染性喉气管炎病毒（ＩＬＴＶ）的鸡胚、鸡胚肾细胞等培养系统进行研究；对病毒包涵体、病毒形态进行观察；对病毒毒价进行测定。结果，病毒在鸡胚绒毛尿囊膜产生痘斑和坏死灶，鸡胚发育不良并致死；鸡胚肾细胞稳定地产生合胞体等细胞病变；绒毛尿囊膜切片经Ｈ－Ｅ梁色，可观察到紫红色嗜酸性核内包涵体充满细胞核；病毒细胞培养物粗提后用负染法电镜观察，绒毛尿囊膜用超薄切片法电镜观察，均可见到病毒颗粒，病毒直径约２４０～３００ｎｍ，核衣壳直径约１００～１４０ｎｍ，外有圆形或椭圆形囊膜；经微量培养系统测定，病毒毒价为１０６．１２ＴＣＩＤ５０／０．０５ｍＬ。     

苹果浑浊汁贮藏过程中浑浊稳定性的研究

为考察苹果浑浊汁在贮藏中的浑浊稳定性，进行了在4、22和40℃贮藏果汁120 d的试验。采用了电子显微镜学、光学显微镜学、Zeta电位和粒径分布分析等技术，结合高效液相色谱(HPLC)分析酚类物质进行研究。结果发现，果汁中相对大尺寸的颗粒先聚集下沉，造成浊度的迅速下降。随着留在瓶上部的大的颗粒数目的减小，颗粒下沉的速率降低。总酚、表儿茶素、绿原酸和单宁的损失随着贮藏温度的升高和储藏时间的延长增大。添加0.006%的维生素C可抑制由酚类物质的氧化聚合产生的不溶性小颗粒的产生，使果汁浊度变化减小。悬浮颗粒的尺寸大于其电性质对浑浊稳定性的影响。     

鲜榨苹果汁陶瓷膜超滤澄清与除菌的中试试验研究

该研究应用膜孔径为100 nm的陶瓷膜错流超滤中试系统(MEMBRALOX^?，Pall)对果胶酶酶解后的鲜榨苹果原汁进行了过滤澄清与除菌效果研究。结果表明，100 nm陶瓷膜错流超滤的最佳操作条件为：跨膜压力为0.85×10⁵ Pa，温度为50℃，膜面流速为5 m/s；以0.5%次氯酸钠和4% NaOH溶液作为清洗剂，膜通量的恢复率可以达到98%。过滤后果汁中的悬浮颗粒和引起浊度升高的大分子胶体物质大部分被滤除，而果汁的各项质量指标如pH值、总酸、糖度等却未发生     

酶解牛乳蛋白多肽复合果汁乳酒工艺研究

为克服传统乳酒缺陷，该文采用蛋白酶水解法及酒精酵母乳酸菌混合发酵法研究了牛乳蛋白多肽复合果汁乳酒的生产工艺。通过对比和正交试验确定了牛乳蛋白的最佳水解酶、水解条件及牛乳蛋白多肽复合果汁乳酒的发酵条件和配方。结果表明：牛乳蛋白的最佳水解酶是中性蛋白酶，最佳水解条件是：酶用量140 mg/L，温度50℃，pH 6.5，酶解5 h,牛乳蛋白水解最彻底；牛乳蛋白多肽复合果汁乳酒的最佳发酵条件为经中性蛋白酶水解的牛乳，用蔗糖调整其糖度为15%，再配以4%的猕猴桃浓缩汁，添加0.35％ kefir发酵剂在25℃发酵12 h，发酵液中的酒精及总酸含量较高；牛乳蛋白多肽复合果汁乳酒的最佳配方组成是：发酵液60%、糖6%、酸0.28%、甜味剂0.1%、稳定剂0.5%、复合香精0.06%、风味增强剂8 mg/L，乳酒品质最好。     

尼罗罗非鱼胰岛的显微和亚显微结构

应用光镜、电镜及特殊染色等技术对尼罗罗非鱼(Tilapia nilotica)的胰岛及其细胞类型和形态进行了详细的研究。尼罗罗非鱼的胰脏与肝脏混合存在，属于肝胰脏。胰岛散布在胰腺内，无固定的形态，胰岛细胞的数量与类型因胰岛的大小而异。用Gomori醛复红特殊染色法，见尼罗罗非鱼胰岛有三种细胞：A细胞胞质中有黄色颗粒；B细胞胞质中有紫红色的颗粒；D细胞胞质内有浅绿色或淡灰色的颗粒。电镜下，B细胞的分泌颗粒较大,芯的形态多样，电子密度差异大,芯与界膜之间常有较大的间隙；A细胞分泌颗粒形态不规则，芯的大小不等，界膜与芯之间无间隙；D细胞分泌颗粒较多，芯的电子密度较低，界膜与芯之间无间隙。此外，胞质内可见较大的线粒体。     

壳聚糖澄清芦柑果汁工艺条件的优化

为了制备稳定的澄清芦柑果汁,该文基于Box-Behnken试验设计,探讨了壳聚糖浓度、澄清温度、澄清时间对果汁澄清度的影响;建立了二次多项式回归模型,分析模型的有效性与因子间的交互作用,并对壳聚糖澄清芦柑果汁的工艺参数进行了优化。结果表明：壳聚糖澄清芦柑果汁的最佳工艺参数为：壳聚糖浓度0.80 g/L、温度59℃和时间71 min。在此最佳工艺条件下果汁透光率达到97.8%,且试验结果与模型预测值（98.3%）相吻合,所得回归模型拟合情况良好（R2=0.9886）,达到设计要求。进一步对经壳聚糖澄清后的芦柑果汁的相关指标进行测定,发现果汁中可溶性固形物、维生素 C 及总酸含量依次从11.30±0.15%、31.33±3.25 mg/100mL、0.71±0.00 g/100mL略降为9.50±0.25%、21.8±5.28 mg/100mL、0.51±0 g/100mL,而总酚、果胶、蛋白质质量浓度依次从990.3±8.02 mg/L、366±4.70μg/mL、595.53±20.62μg/mL减少为557.87±4.67 mg/L、186.24±44.32μg/mL、26.42±0.30μg/mL 有较明显下降,但澄清后的果汁非生物稳定性很好。该试验用响应面法优选出的澄清工艺合理可行,为芦柑果汁深加工及果汁产品开发提供了理论依据。     

相对光照度对富士苹果品质的影响

富士苹果树冠不同层次、部位相对光照度和果实品质分析表明，相对光照度从树冠上层到下层、外围到内膛逐渐降低，果实品质差异明显；应用一元二次回归建立相对光照度对富士苹果品质因素影响的回归方程，求解出果实品质指标最大的相对光照度，果实花青素含量对光的要求较高，相对光照度７７．９１％为富士苹果花青素形成的最佳相对光照度，果实可溶性固形物和总糖的最适相对光照度为６０％，其它各品质因素对相对光照度要求较低，但均在５２％以上。     

杀雄剂SQ-1诱导小麦雄性不育花药蛋白质组分分析

采用固相pH梯度SDS聚丙烯酰胺双向凝胶电泳技术对杀雄剂SQ-1处理和未处理的小麦单核期、二核期花药总蛋白进行了分离，通过考马斯亮蓝G-250染色，获得了分辨率和重复性较好的双向电泳图谱。通过PDQuest 2DE图像分析软件的分析，在等电点(pI)4～7之间可识别约500个以上较为清晰的蛋白质点，处理和对照各时期蛋白质在等电点5～6，分子量20～40kD之间相对较集中；检测到单核期差异点43个，二核期差异点45个，并计算出了各差异点的分子量和等电点。其中11个点在处理材料的单核期缺失而在对照中表达，7个在处理中表达而在对照中缺失，14个点表达量在处理中明显减弱，而另外11个明显增强；在二核期45个差异点中，有13个在处理中缺失而在对照中表达，7个在处理中表达而在对照中不表达，12个表达量在处理中明显减弱而另外13个明显增强。经SQ-1处理后在单核期和二核期A-Z3（26.8/5.7）和C-Z5（26.8/5.7）点均缺失。点A-L10(26.8/5.9)在单核期处理的表达量下调，而到了二核期完全缺失C-Z6（26.9/5.9）点。通过双向电泳技术获得的这些差异蛋白可能直接或间接地参与了花药发育的各个途径，因此，处理和对照图谱中表现出的差异蛋白很可能与SQ-1诱导小麦雄性不育有关。     

变温压差膨化法制备冷泡茶的工艺优化

为优化变温压差膨化法制备冷泡茶的工艺，研究了含水率、冷冻处理次数和膨化温度对冷泡茶水浸出物的影响。通过单因素和正交试验优化了冷泡茶的加工工艺。正交试验结果表明，影响冷泡茶水浸出物的因素按影响程度大小排序从高到低依次为含水率、冷冻次数、膨化温度。冷泡茶制备的优化工艺为：茶叶含水率50%，-18℃下冷冻处理3次，每次24 h，膨化温度115℃。在此最优条件下制备的冷泡茶，经室温下冷水浸泡30 min后，冷泡茶茶汤的主要生化成分：水浸出物质量分数、咖啡碱质量分数、茶多酚质量分数、游离氨基酸质量分数、可溶性糖质量分数分别为16.45%、0.84%、11.45%、0.93%、2.47%。结果表明应用变温压差膨化法制备的冷泡茶的生化成分在室温下更易浸出，该研究为冷泡茶工业化生产提供技术支持。     

棉铃虫精子的超微结构及对其辐照后变化的初步观察

利用透射电子显微镜技术，研究了棉铃虫（ＨｅｌｉｃｏｖｒｐａａｒｍｉｇｅｒａＨｕｅｂｎｅｒ）真核精子和无核精子的超微结构，比较了在经γ射线照射的棉铃虫精子与未照射虫精子结构的差异，结果表明，棉铃虫真核精子和无核精子的顶体结构有较大差异。真核精子有核，呈半月形，鞭毛线粒体衍生物与微管系统紧密结合，从头到尾在质膜上都覆盖许多特定结构的外长物；无核精子没有核，顶体和鞭毛通微管连接，鞭毛缄粒体衍生物与微管系     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

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.     

Genetic similarities among Spanisch populations of Agropyron, Elymus and Thinopyrum, using PCR-based markers

Arbitrary oligonucleotides were used as primers to amplifygenomic DNA of 48 wild Spanish populations of Agropyroncristatum, Elymus hispanicus,E. caninus,E. repens,Thinopyrum curvifolium, Th.junceum and Th.intermedium. Genetic diversity was analysedusing nineteen primers. The number of amplified products ranged from8 to 18 per primer and a total of 240 markers were scored. Differentlevels of intraspecific genetic diversity were found, the allogamousspecies E. repens andTh. intermedium being themost variable. Jaccard's similarity coefficients for internalmeasure within and between populations were used to produce a clusterdiagram. The results demonstrate differences in the degree ofsimilarity between taxonomic units. Interpopulational variability andinterspecific genomic relationships of these species arediscussed.     

Mycorrhizae,biocides, and biocontrol. 4. Response of a mixed culture of arbuscular mycorrhizal fungi and host plant to three fungicides

The effects of three commonly used fungicides on the colonization and sporulation by a mixture of three arbuscular mycorrhizal (AM) fungi consisting of Glomus etunicatum (Becker & Gerd.), Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, and Gigaspora rosea (Nicol. & Schenck) in symbiosis with pea plants and the resulting response of the host-plant were examined. Benomyl, PCNB, and captan were applied as soil drenches at a rate of 20 mg active ingredient kg^-1 soil 2 weeks after transplanting pea seedlings in a silty clay-loam soil containing the mixed inocula of AM fungi (AM plants). Effects of fungicides were compared to untreated plants that were inoculated with fungi (AM control). The effect of mycorrhizal inoculation on plant growth was also examined by including nonmycorrhizal, non-fungicide-treated plants (non-AM control). Fungicides or inoculation with AM fungi had only a small effect on the final shoot weights of pea plants, but had greater effects on root length and seed yield. AM control plants had higher seed yields and lower root lengths than the corresponding non-AM plants, and the fungicide-treated AM plants had intermediate yields and root lengths. Seed N and P contents were likewise highest in AM control plants, lowest in non-AM plants, and intermediate in fungicide-treated AM plants. All three fungicides depressed the proportion (%) of root length colonized by AM fungi, but these differences did not translate to reductions in the total root length that was colonized, since roots were longer in the fungicide-treated AM plants. Pea plants apparently compensated for the reduction in AM-fungal metabolism due to fungicides by increasing root growth. Fungicides affected the population of the three fungi as determined by sporulation at the final harvest. Captan significantly reduced the number, relative abundance, and relative volume of G. rosea spores in the final population relative to the controls. The relative volume of G. etunicatum spores was greater in all the fungicide-treated soils, while G. mosseae relative volumes were only greater in the captan-treated soil. These findings show that fungicides can alter the species composition of an AM-fungal community. The results also show that AM fungi can increase seed yield without enhancing the vegetative shoot growth of host plants.