几种常见桑树病害的识别与防治

桑树是蚕桑产业的重要物质基础。为确保桑树健康成长,促进产业发展,桑树病害的有效识别与及时防控尤为重要。真核微生物、原核微生物及非细胞类病毒中均存在能引发桑树传染性病害的病原微生物。其中由真核微生物引起的桑里白粉病与桑椹菌核病,原核微生物引起的桑青枯病与桑疫病是爆发频繁、危害极大的桑树病害。本文就这四种桑树病害的病原、侵染循环、病害识别及防治方法等进行系统梳理,并简要介绍几种非细胞类微生物引起的桑树病害,以期为生产上防治相关病害提供参考。     

鲈鱼摩氏摩根菌的鉴定及药敏试验

从患病鲈鱼体内分离到1株优势菌LY2014,对其进行形态观察、生理生化试验、16SrDNA基因序列分析,同时采用Kriby-Bauer纸片扩散法进行耐药性分析。结果该菌为发酵型、具有动力的革兰阴性杆菌,根据生化试验结果初步确定该菌为摩氏摩根菌。以该菌的基因组为模板PCR扩增获得的16SrDNA序列长度为1 407bp(GenBank登入号为KJ830813)。该序列与GenBank数据库中摩氏摩根菌的16SrDNA基因序列相似性高达99%,系统进化树显示其与摩氏摩根菌亲缘关系最近,从而确定菌株LY2014为摩氏摩根菌。该菌株对磷霉素、菌必治和多黏霉素B高度敏感,对痢特灵、红霉素和诺氟沙星等5种药物中度敏感,对氨苄西林和氟苯尼考等11种药物耐药。     

北京地区奶牛隐性乳房炎金黄色葡萄球菌的分离鉴定及药敏试验

为了解北京地区奶牛隐性乳房炎中金黄色葡萄球菌的感染情况及对常用药物的敏感性,用科玛嘉显色培养基和16SrRNA PCR检测方法对5个奶牛场的100份隐性乳房炎奶样进行金黄色葡萄球菌的分离鉴定,采用K-B纸片扩增法进行药敏试验。结果表明,显色培养基分离到24株疑似金黄色葡萄球菌,经16SrRNA PCR鉴定,15株为金黄色葡萄球菌;药敏试验结果显示,15株金黄色葡萄球菌均对β-内酰胺类中的氨苄西林产生普遍耐药性,对克林霉素和环丙沙星的耐药率较高,分别为53.33%和40%;对氧氟沙星、庆大霉素、头孢噻肟和头孢曲松的耐药性较低,耐药率为6.67%。说明15株金黄色葡萄球菌分离株对7类9种抗菌药物都有不同程度的耐药性。     

饲用小黑麦在海河平原区的生产性能及适应性评价

在海河平原区对11个饲用小黑麦品种进行了生产性能比较试验以及旱作条件下适应性,试验得出:冀饲-1成熟早,生育期短,抽穗期比对照中新830提前6d,干草产量高,比对照中新830提高26.7%,能与春播作物形成一年两作,适于在海河平原区推广利用;冀饲-2在海河平原地区鲜干草产量均较高,分别比对照中新830增产4 854.3kg/hm2和777.0kg/hm2,属于高产品种,茎叶比低,叶量丰富是海河平原区主要品种推广种植。旱作条件下种植,饲用小黑麦株高比正常管理条件下降低64.6%~83.4%,分蘖数和成穗数分别减少60.0%~74.7%和85.3%~98.1%,鲜干草产量分别降低69.3%和70.2%,利用价值不大,只有在一定的灌溉和施肥条件下种植才能产生较好经济效益。     

Pyrantel resistance in two herds of donkey in the UK

Resistance to currently available anthelmintics is a serious phenomenon which is prevalent globally. Cyathostomins are one of the major parasites, and are of primary concern in donkeys. There have been reports of emerging resistance to pyrantel, but the status of pyrantel resistance in donkey populations in the UK is largely unknown. This report investigates pyrantel resistance in two geographically isolated donkey herds in the South West of England. The first herd had suspected pyrantel resistance, with already established resistance to other anthelmintics. In the second herd the efficacy of pyrantel was not suspected at the time the study took place. Faecal Egg Count Reduction Test (FECRT) was carried out, revealing large scale resistance. Eighty one percent of the first herd and 73% of the second herd had a FEC of less than 95% after treatment, and anthelmintic resistance was confirmed using the World Association for the Advancement of Veterinary Parasitology guidelines. These findings indicate that anthelmintic resistance to pyrantel exists in both tested donkey populations and illustrate the continuing development of resistance through different classes of chemotherapeutics.     

Evaluation of the drug sensitivity and expression of 16 drug resistance-related genes in canine histiocytic sarcoma cell lines

Canine histiocytic sarcoma (HS) is an aggressive tumor type originating from histiocytic cell lineages. This disease is characterized by poor response to chemotherapy and short survival time. Therefore, it is of critical importance to identify and develop effective antitumor drugs against HS. The objectives of this study were to examine the drug sensitivities of 10 antitumor drugs. Using a real-time RT-PCR system, the mRNA expression levels of 16 genes related to drug resistance in 4 canine HS cell lines established from dogs with disseminated HS were determined and compared to 2 canine lymphoma cell lines (B-cell and T-cell). These 4 canine HS cell lines showed sensitivities toward microtubule inhibitors (vincristine, vinblastine and paclitaxel), comparable to those in the canine B-cell lymphoma cell line. Moreover, it was shown that P-gp in the HS cell lines used in this study did not have enough function to efflux its substrate. Sensitivities to melphalan, nimustine, methotrexate, cytarabine, doxorubicin and etoposide were lower in the 4 HS cell lines than in the 2 canine lymphoma cell lines. The data obtained in this study using cultured cell lines could prove helpful in the developing of advanced and effective chemotherapies for treating dogs that are suffering from HS.     

草酸诱导紫花苜蓿对霜霉病的抗性

为确定外源草酸(OA)对紫花苜蓿(Medicago sativa)抗霜霉病(Peronospora aestivalis)的诱导作用,本研究采用喷雾法将10、20、30、40 mmol·L-1的草酸喷洒在十叶期紫花苜蓿幼苗上,喷雾后7 d测定苜蓿霜霉病苗期病情指数,并分别于喷雾后1、3、5、7和9 d测定叶片过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)和超氧化物歧化酶(SOD)的活性。结果表明,喷雾10~40 mmol·L-1草酸溶液均可降低苜蓿霜霉病的病情指数,且随着草酸浓度升高,病情指数由31.1%下降到19.6%,下降了11.5百分点,相对诱导抗病效果呈上升趋势,最高诱抗效果达到50.8%,苜蓿叶片中POD、PAL和SOD的活性增强。     

茉莉酸甲酯和磷酸氢二钾诱导柱花草对炭疽病的抗性

探究茉莉酸甲酯(Methyl Jasmonate,MeJA)和磷酸氢二钾(K2HPO4)诱导柱花草对炭疽病的抵抗作用。结果表明,二者浓度分别为0.001~0.1mg·mL-1和10~50mmol·L-1时,病情指数均显著降低(P0.05),最佳诱导浓度分别是0.001mg·mL-1和30mmol·L-1,诱导效果分别是64.84%和54.40%。0.001mg·mL-1MeJA处理组的过氧化物酶(POD)及多酚氧化酶(PPO)活性在48h达到最大值,显著高于对照组。30mmol·L-1 K2HPO4处理组的POD与PPO活性分别在48和24h达到最大值,显著高于对照组。两种诱抗剂处理的POD和PPO活性在接种早期增加了柱花草对炭疽菌的侵染的抵御能力,进而提高植株的抗病性。30mmol·L-1 K2HPO4处理组的过氧化氢酶(CAT)活性在48~72h内上升,显著高于对照组,而0.001mg·mL-1 MeJA处理组的CAT活性除72h显著低于对照组,其他时间点与对照组相差不大。说明在诱导柱花草抗病性方面,两种诱导抗性剂处理的诱抗效果与POD、PPO和CAT的酶活性的诱导的时间及程度有关。