兰州市高海拔旱作区娃娃菜栽培技术

在分析兰州市高海拔地区自然条件的基础上,有针对性地提出了高海拔旱作区娃娃菜栽培技术,以供参考。     

冷冲高硬度材料模具失效的原因与对策研究

在日常的应用中,我们发现,制作材料是高合金钢的模具要比硬质合金制作的模具耐用,我们进而研究了其失效的方式以及失效的比例,研究结果显示,硬质合金的失效主要体现在掉渣和崩刃,而高合金钢的失效主要体现在正常的磨损方面。在制作的过程中,高合金钢会由于在加热的不适当而使得碳化物不均匀,或者使得硬度不稳定等原因而没有充分发挥材料的潜在能力,文章对如何提高高合金钢的寿命提出了具体方案。     

春花生超高产栽培技术模式研究与应用

采取正交旋转回归设计,以播种期、种植密度、施肥量为试验因子,以9000kg/hm2为产量目标函数,进行春花生超高产栽培模式集成研究。结果表明,在鲁西南平原地区,超高产春花生以种植密度和N、P、K施肥量为主要限制因素,播种期为次要限制因素。明确了春花生单产达到9000kg/hm2以上的最佳种植密度、播种期和合理的N、P2O5、K2O施用量为主要指标的栽培技术模式,增产效果显著。     

晚稻机收留高茬紫云英迟播技术的应用效果研究

通过田间试验,研究了双季稻田晚稻机械收获留高茬后紫云英迟播的应用效果。结果表明,与传统紫云英播种技术相比,晚稻机械收获留高茬紫云英迟播显著缩短了紫云英的生育期,但其盛花期能保持与传统播种技术一致,对下茬早稻作物的种植没有影响;两种播种方法对盛花期鲜草产量、植株养分含量和养分积累量均没有显著影响,说明迟播播种能达到与传统播种一样的肥田目的;迟播对紫云英的种子产量及产量构成因素均没有明显影响,与传统播种技术相比可节约劳动力成本约45元/hm2,且可避免传统播种方法对晚稻植株的伤害。在现代双季稻种植条件下,晚稻机械收获留高茬紫云英迟播技术具有较大的优势和发展前景。     

PA-X基因的长度变化对H3N2犬流感病毒复制能力和致病性的影响

H3N2犬流感病毒(canine influenza virus, CIV)已在中国多地的犬群中流行,是禽流感跨宿主感染并形成新分支的近期案例。研究表明,PA-X基因与甲型流感病毒适应新宿主的能力相关,且其长度能够影响甲型流感病毒的复制及致病能力。为了解PA-X基因的长度变化对H3N2 CIV复制能力及致病力的影响,本研究利用H3N2 CIV的8质粒操作系统,拯救了三株重组H3N2 CIV毒株：PA-X基因表达大小为232个氨基酸多肽的亲本病毒CIV＿PA-X＿232;对PA编码区第191、192位氨基酸的密码子进行改造,PA-X基因不表达蛋白的重组病毒CIV＿PA-X＿Knock;对PA+1编码区第232位氨基酸进行突变,PA-X基因表达大小为252个氨基酸多肽的重组病毒CIV＿PA-X＿252。通过比较3株重组病毒的聚合酶活性,在MDCK细胞中的复制效率及对小鼠致病性的差异,来评价表达不同长度的PA-X基因对H3N2 CIV的影响。结果显示,CIV＿PA-X＿252和CIV＿PA-X＿Knock的聚合酶活性显著(P<0.05)高于CIV＿PA-X＿232,且CIV＿PA-X＿...     

一例猪繁殖与呼吸综合征高致病性毒株与链球菌混合感染的实验室诊断

某规模化自繁自养猪场产房母猪出现流产,保育猪关节肿胀、倒地不起、大量死亡,为研究发病原因,采集流产胎儿、死亡仔猪的肺脏、脾脏、淋巴结和关节液,进行分子生物学检测,病毒和细菌分离鉴定,并检测不同胎龄母猪猪繁殖与呼吸综合征病毒抗体,结果显示猪繁殖与呼吸综合征病毒检测为阳性,使用PAM分离到一株猪繁殖与呼吸综合征病毒,经序列鉴定为高致病性毒株;抗体结果表明四胎及以上母猪猪繁殖与呼吸综合征病毒抗体阳性率异常升高;病料分离的细菌经鉴定为猪链球菌,经实验室诊断确定猪场发病的原因为猪繁殖与呼吸综合征高致病性毒株与猪链球菌混合感染。     

Hemagglutinin glycosylation modulates the pathogenicity and antigenicity of the H5N1 avian influenza virus

The location and number of glycosylation in HA proteins exhibit large variations among H5 subtype avian influenza viruses (AIVs). To investigate the effect of glycosylation in the globular head of HA on the pathogenicity and antigenicity of H5N1 AIVs, seven rescued AIVs differing in their glycosylation patterns (144N, 158N and 169N) within the HA globular head of A/Mallard/Huadong/S/2005 were generated using site directed mutagenesis. Results showed that loss of glycosylation 158N was the prerequisite for H5 AIV binding to the α2,6-linked receptor. Only in conjunction with the removal of the 158N glycosylation, the H5 AIVs harboring both 144N and 169N glycosylations obtained an optimal binding preference to the α2,6-linked receptor. Compared with the wild-type virus, growth of viruses lacking glycosylation at either 158N or 169N was significantly reduced both in MDCK and A549 cells, while replication of viruses with additional glycosylation 144N was significantly promoted. Mutant viruses with loss of 158N or 169N glycosylation sites showed increased pathogenicity, systemic spread and pulmonary inflammation in mice compared to the wild-type H5N1 virus. In addition, chicken studies demonstrated that inactivated de-glycosylation 169N mutant induced cross-reaction HI and neutralization antibody against various clades of H5N1 AIVs. Moreover, this type of glycan pattern vaccine virus provided better cross-protection in chickens compared to wild-type vaccine virus. Thus, the glycosylation alteration of HA should be considered in the global surveillance and vaccine design of H5 subtype AIVs.     

Suppression of influenza virus infection by the orf virus isolated in Taiwan

Orf virus (ORFV), a member of parapoxvirus, is an enveloped virus with genome of double-stranded DNA. ORFV causes contagious pustular dermatitis or contagious ecthyma in sheep and goats worldwide. In general, detection of viral DNA and observing ORFV virion in tissues of afflicted animals are two methods commonly used for diagnosis of orf infection; however, isolation of the ORFV in cell culture using virus-containing tissue as inoculum is known to be difficult. In this work, the ORFV (Hoping strain) isolated in central Taiwan was successfully grown in cell culture. We further examined the biochemical characteristic of our isolate, including viral genotyping, viral mRNA and protein expression. By electron microscopy, one unique form of viral particle from ORFV infected cellular lysate was demonstrated in the negative-stained field. Moreover, immunomodulating and anti-influenza virus properties of this ORFV were investigated. ORFV stimulated human monocytes (THP-1) secreting proinflammatory cytokines IL-8 and TNF-α. And, pre-treatment of ORFV-infected cell medium prevents A549 cells from subsequent type A influenza virus (IAV) infection. Similarly, mice infected with ORFV via both intramuscular and subcutaneous routes at two days prior to IAV infection significantly decreased the replication of IAV. In summary, the results of a current study indicated our Hoping strain harbors the immune modulator property; with such a bio-adjuvanticity, we further proved that pre-exposure of ORFV protects animals from subsequent IAV infection.     

纳米疫苗在禽流感防控中的研究进展

禽流感病毒(Avian influenza virus,AIV)因其具有变异性强、亚型种类多、感染宿主多样性等特点,对畜牧业发展及公共卫生安全具有巨大的影响。目前,传统灭活疫苗在预防禽流感中虽起着重要作用,但仍存在免疫失败、多次接种及易出现不良反应等弊端,因此,研制新型疫苗来弥补传统疫苗的不足非常有必要。纳米颗粒疫苗具有包裹性好、结构稳定、靶向性高和免疫原性强等优点,可作为新型流感病毒疫苗的候选。笔者首先介绍了禽流感难以防控的原因及纳米疫苗的特点,然后对病毒样颗粒疫苗、自组装蛋白疫苗、聚合物纳米颗粒疫苗、无机纳米颗粒疫苗及纳米颗粒的毒性机制方面进行综述,概述了近年来AIV纳米颗粒疫苗的研究进展,并简述了采用不同抗原、不同纳米材料及不同给药方式对免疫效果的影响,结合目前纳米疫苗的研究,预测了未来纳米颗粒疫苗可作为AIV防控的一种新途径,对禽流感纳米疫苗在兽医临床的应用前景进行了分析和展望。     

阶段性极端高温对七星瓢虫生长发育和繁殖的影响

为明确极端高温天气对七星瓢虫Coccinella septempunctata生长发育和繁殖的影响,通过模拟田间高温发生情况,设置6h极端高温(36℃和39℃)与不同持续时间(1d和3d)对七星瓢虫卵和成虫进行胁迫,以25℃恒温饲养处理为对照,观察统计其发育历期、存活率、繁殖力及子代孵化率。结果表明,在相同高温胁迫模式下,七星瓢虫成虫的耐热性要明显高于卵,如在39℃处理1d后,卵和成虫的存活率分别为52.09%和93.94%;处理温度越高,高温持续时间越长,七星瓢虫卵的存活率越低,36℃处理1、3d和39℃处理1、3d后卵的存活率依次为71.31%、62.87%、52.09%和24.98%。七星瓢虫卵经39℃处理3d后,其孵化1龄幼虫的发育历期为2.77d,显著长于对照组(2.11d),其余龄期幼虫的发育历期、整个幼虫期和蛹期与对照组均无显著差异,说明七星瓢虫发育前期经历极端高温可能会导致其发育后期生长加速,出现生长补偿现象。卵期受极端高温的影响要显著大于成虫期,卵和成虫在39℃处理1d后的单雌产卵量分别为42.67粒和139.79粒;所有高温处理组的子代卵孵化率均显著低于对照组(85.42%),介于0~64.13%之间。另外,各高温处理组的种群趋势指数在5.26~56.02之间,均低于对照组(78.76)。表明夏季极端高温天气频发可能导致七星瓢虫种群数量减少,不建议此时期在田间释放七星瓢虫卵进行害虫防控。