Detection of citrus psorosis-ringspot virus using RT-PCR and DAS-ELISA

Psorosis, sometimes also associated with ringspot symptoms, is a widespread and damaging disease of citrus in many parts of the world including South America and the Mediterranean basin. We describe the application of RT-PCR and DAS-ELISA diagnostics to an isolate of citrus ringspot virus (CtRSV-4) and other virus isolates associated with this disease. Fragments of cDNA from bottom-component RNA of CtRSV-4 were cloned and sequenced, and PCR primers were designed, 5'ACAATAAGCAAGACAAC upstream, and 5'CCATGTCACTTCTATTC downstream. RT-PCR experiments using these primers allowed detection of CtRSV-4 in infected citrus leaves down to a tissue dilution of 1/12 800 representing 2 μg of tissue, and less sensitive detection of the related citrus psorosis-associated virus (CPsAV90-1-1) and four other psorosis isolates from Argentina and the USA. In addition, CtRSV-4 particles were partially purified from local lesions in Chenopodium quinoa, and the preparations used to raise a rabbit antiserum. The antiserum was absorbed with extracts of healthy C. quinoa leaves, and a DAS-ELISA kit was prepared and tested for detection of CtRSV-4, CPsAV90–1-1, and other psorosis isolates from Argentina, the USA, Italy and Spain. The ELISA detected CtRSV-4 down to a tissue dilution of 1/1600, and most other psorosis isolates down to dilutions of 1/200–1/800. Three of a total of 20 heterologous isolates were consistently negative. Comparison of the PCR and ELISA results suggests that both methods can be used for detection of a range of psorosis isolates, but that variation of the viruses in the field might cause problems for any one diagnostic test.     

低磷胁迫对小麦镉吸收的影响

为探究低磷胁迫下小麦根系生理和形态的变化及其对镉的吸收能力的影响,以Ca₃（PO₄）₂作为磷源,通过砂培试验研究了在低磷胁迫下小麦根系形态和分泌物变化特征,以及这些变化对难溶态镉（CdCO₃）的活化与吸收的影响。结果表明,在低磷处理中,小麦地下部生物量显著低于对照,降幅为27.3%（P<0.05）,根长度、根表面积和根体积均显著变小（P<0.05）。此外,低磷胁迫下小麦地上部和地下部磷含量均显著降低,降幅分别为35.4%和23.1%（P<0.05）,但是显著促进了难溶态磷的溶解（P<0.05）。同时还发现低磷胁迫显著提高了小麦植株Cd含量和Cd的总活化量,增幅分别为190.8%和82.8%（P<0.05）。低磷胁迫下培养基pH降低了0.3,同时根中草酸根和苹果酸根含量显著升高,增幅分别为1 588.1%和37.7%（P<0.05）,由此可见,低磷胁迫下小麦通过分泌质子和羧酸根促进了磷的活化,并促进了Cd的活化,进而导致小麦Cd吸收的增加。这些结果阐明了低磷胁迫影响小麦Cd吸收的机制。     

成熟期短时渍水胁迫对烤烟碳氮代谢关键酶及主要碳、氮化合物含量的影响

以烤烟云烟97为材料,采用田间试验研究了成熟期短时渍水处理对烤烟碳氮代谢关键酶活性及主要碳、氮化合物含量的影响。结果表明,在烤烟成熟期渍水处理3 d,中部叶片硝酸还原酶活性低于对照,降幅为20.39%;转化酶和淀粉酶活性高于对照,增幅分别为33.14%,56.70%;烟叶淀粉、总氮和烟碱含量有降低趋势,分别下降了2.9,0.74,0.77个百分点,而总糖和还原糖含量有增加趋势,分别上升了1.33,0.46个百分点。说明渍水胁迫使叶片生理代谢紊乱,氮代谢减弱,碳水化合物积累减少。研究结果有助于从生理生化角度揭示成熟期渍水胁迫对烤烟生长和品质形成影响的机制。     

Reproductive Performance of Rabbit Does Artificially Inseminated via Intravaginal Administration of [des-Gly 10, d-Ala6]-LHRH Ethylamide as Ovulation Inductor

This study was aimed to evaluate the reproductive performance of rabbit does artificially inseminated (AI) with a GnRH analogue [des‐Gly10, d ‐Ala6]‐LHRH. ethylamide to induce ovulation by intravaginal administration, delivered in the seminal dose. In a preliminary experiment, 39 does were divided into three groups (n = 13) that, at the time of AI, received the following ovulation induction treatments: (i) control group: 20 μg of gonadorelin administered intramuscularly; (ii) 25 μg of the GnRH analogue added to the seminal dose; (iii) 30 μg of the GnRH analogue added to the seminal dose. Fertility did not differ between the three groups (control: 80.6%, group 2: 82.8%, group 3: 73.3%). In a second experiment, a large‐scale field trial was conducted to test the use of 25 μg of the GnRH analogue [des‐Gly10, d ‐Ala6]‐LHRH ethylamide delivered in the seminal dose (n = 270) against 20 μg of gonadorelin administered intramuscularly. Fertility was higher (p < 0.05) when ovulation was induced by intravaginal administration of the GnRH agonist (91.1% vs 85.6%). Prolificacy or mortality at birth was never affected by the ovulation induction treatments. In a third experiment, two groups of does [control group (n = 39): ovulation was induced using 20 μg of gonadorelin administered intramuscularly; treatment group (n = 40): ovulation was induced using 25 μg of [(des‐Gly10, d ‐Ala6)‐LHRH ethylamide added to the seminal dose] were inseminated at 42‐day intervals for five successive AI cycles, to test the response to the GnRH agonist after repeated intravaginal administration to the same animals. Fertility and prolificacy were not influenced by the ovulation induction treatment neither there was an interaction between treatment and parity. The last experiment was aimed to determine whether it could be possible to add the GnRH agonist to the semen in the AI Center, just after semen collection and dilution, or it would have to be added in the farm, immediately before AI. Kindling rates did not significantly differ when ovulation was induced by intramuscular injection of gonadorelin (84.5%) or when the GnRH agonist was added to the seminal dose just at the moment (93.8 %) or 24 h before AI (90.4 %), but it was significantly lower when the hormone was added to the semen 32 h before AI (76.3 %). Prolificacy, however, was not influenced by the ovulation induction treatment.     

BOOK REVIEW

The 5-MinuteVeterinary Consult: Canine and Feline . 2nd edn. Tilley LP, Smith FWK, Lippincott Williams & Wilkins     

大通牦牛推广十年的回顾与展望

从2003年以来青海省大通种牛场开始了较大面积的推广工作,到今年己有10年的推广历史了。对一个新品种大面积推广10年是一个极为重要的时间节点。2005年农业部批准"大通牦牛"为新品种并决定颁发新品种证书。截止2013年前己向青海省6州1地1市39个县累计推广大通牦牛种公牛14 640余头,据2013年不完全统计,大通牦牛后裔在省内推广区达91万头以上。今后必需加快品系繁育提高大通牦牛整体水平;加强核心育种群管理确保种牛质量;加强种公牛的动态溯源管理;组识种牛场技术人员深入推广区,传授良种良养的配套技术和野外冷配技术。     

青海省海南州高寒草地荒漠化治理技术与对策

总结了海南州高寒干旱草地荒漠化特征和成因,分析出气候变化、毁草开荒、超载过牧、鼠类危害、利用不当、执法不严等是草地荒漠化的主要原因,通过对荒漠化草地实行人工补播优良牧草、灭除毒草、消灭鼠害、禁牧封育、暖棚养畜、营造饲料护牧林等措施,提出了防止草地荒漠化的对策及治理技术.     

云南农业大学信息服务与用户调查研究分析

 通过对云南农业大学的教师、研究生和本科生的信息需求调查,了解到各类用户利用文献信息的状况和对文献信息的需求,为图书馆开展信息服务提供了依据。     

镉在黄瓜幼苗中的化学形态及亚细胞分布

为探究黄瓜幼苗对镉的吸收累积特性,将黄瓜幼苗置于6种镉浓度梯度(0、10、50、100、200、300μmol·L~(-1))营养液中培养17 d,测定黄瓜幼苗地上部和根部的镉含量以及镉在叶片的亚细胞分布和其化学形态分布。结果表明:随镉浓度升高,转移系数逐渐降低,黄瓜由根向地上部对镉的转运能力减弱。时间或浓度处理均会显著增加黄瓜叶片各亚细胞组分镉含量,镉的富集比例趋势表现为可溶性部分细胞壁细胞器,其中可溶性部分镉含量占44.88%～84.94%,远大于细胞器(3.10%～17.05%)与细胞壁(11.20%～39.66%)。相同时间下,随镉处理浓度的增加,镉在细胞壁组分占比先升高后降低,可溶性部分镉的占比先降低后升高。同时随着处理时间延长,细胞壁组分镉占比降低,可溶性部分镉占比升高。黄瓜叶片中NaCl提取态镉占比最高(33.69%～54.23%),但随着镉浓度提高,乙醇提取态、H2O提取态镉占比升高。当镉浓度达到300μmol·L~(-1)时,黄瓜叶片中的镉形态以乙醇提取态、H2O提取态和NaCl提取态占优势。总的来看,在器官水平上,黄瓜通过限制镉由根部向地上部传递的方式,降低镉对黄瓜地上部的毒害;亚细胞水平上,细胞壁对镉的吸持和液泡区室化是黄瓜对镉胁迫下的重要解毒方式,其中以液泡的区室化占主导位置;在化学形态分布上,镉的化学形态转化也是黄瓜应对镉胁迫的重要耐性策略。     

西藏拉鲁湿地土壤酵母菌多样性及产胞外 酶活性菌株分布特性研究

采用平板稀释法从西藏拉鲁湿地土壤中分离酵母菌,开展城市湿地酵母菌多样性研究。结合经典分类法及26S rDNA D1/D2区域序列分析,对获得的酵母菌菌株进行系统分类,并进行产胞外酶活性菌株的皿内初筛。结果显示,分离得到的83株酵母菌分属于隐球菌属Cryptococcus、假丝酵母属Candida、原囊菌属Protomyces、红酵母属Rhodotorula及孢囊线黑粉酵母Cystofilobasidium等5个属16个种,其中胶红酵母Rhodotorula mucilaginosa相对丰度最高,约26%,其次为维多利亚隐球酵母Cryptococcus victoriae和山杨隐球酵母Cryptococcus aspenensis;多样性分析表明,LhWS6样点的酵母菌多样性最丰富,LhWS9样点则最低;产胞外酶活性菌株初筛结果表明,25℃下产脂肪酶活性菌株比例最高,为67%,而4℃下产淀粉酶活性菌株数最多,为49株。另外,低温条件下产淀粉酶、果胶酶、纤维素酶和几丁质酶的活性菌株比例均高于常温条件。结果表明拉鲁湿地土壤酵母菌总体种类较丰富,但每个样点的种类相对单一,说明湿地生境或人为活动一定程度影响到该生态环境酵母菌的种群分布,开发青藏高原耐低温、产胞外酶等活性菌株具有一定的应用前景。