副黏病毒V蛋白抗干扰素作用的研究进展

副黏病毒的V蛋白是结构蛋白P基因内使用不同的阅读框编码产生的一种非结构蛋白,具有抗干扰素(IFN)的作用。副黏病毒科不同成员间V蛋白的产生机制不同,国内外利用反向遗传、RNA干扰等技术缺失或抑制V蛋白,通过检测IFN产生及作用通路上关键蛋白的变化情况研究其抗IFN作用机制,发现副黏病毒V蛋白既可直接阻止IFN产生,也可阻断IFN抗病毒JAK/STAT作用通路。文章对副黏病毒V蛋白、干扰素的产生及其抗病毒作用机制,特别是V蛋白抗IFN作用的研究进展及应用前景做一综述。     

马A3Z3V1抑制马传染性贫血病毒早晚期反转录的鉴定

马A3Z3V1是宿主细胞内的一种APOBEC3免疫因子,它可以有效抑制马传染性贫血病毒(EIAV)在马宿主细胞内的复制.为鉴定马A3Z3V1分子对EIAV早晚期反转录的抑制作用,本实验根据EIAV的R/U5和gag基因序列分别设计了检测EIAV早晚期反转录产物的引物并建立了SYBR Green Ⅰ荧光定量PCR方法,利用该方法评价免疫因子A3Z3V1对EIAV逆转录过程的影响.结果显示,在早期反转录过程中,A3Z3V1可以使EIAV的反转录产物最高减少7倍;在晚期反转录过程中,A3Z3V1可以使EIAV的反转录产物最高减少3倍.本实验结果将有助于进一步研究APOBEC3分子的抗病毒作用机制.     

鸡新城疫减蛋综合征异源二联灭活油苗的研究

鸡新城疫（ＮＤ）病毒和减蛋综合征（ＥＤＳ－７６）病毒混合种接种在１２—１４日龄鹅胚上，在接种后１２０小时收获尿囊液，用０．４％甲醛溶液３７℃２４小时灭活，加入１０号白油，制成鸡新城疫减蛋综合征异源二联苗，经２０余万只鸡试用表明，该苗能有效地控制ＮＤ和ＥＤＳ－７６的发生     

SYBR Green I荧光RT-PCR法检测H5亚型禽流感病毒

用2株不同致病力的H5亚型禽流感病毒(AIV)感染Madin-Darby canine kidney(MDCK)细胞,收集感染后6,12,24,48,72 h的病毒,提取总RNA,利用Rotor Gene RG3 000实时定量PCR仪对H5亚型AIV的HA基因进行检测,试图建立快速检测H5亚型AIV的real-time RT-PCR方法,并用所建立的方法对来自全国各地的疑似H5亚型AIV的病料和咽喉拭子、泄殖腔拭子346份进行检测。结果表明：农业部动物流感重点开放实验室建立的HA基因的teal-time RT-PCR方法可以检测到细胞培养物中和临床样品中是否含有H5亚型AIV,与常规RT-PCR比较,该方法更加特异、准确、快速。     

我国棉蚜对吡虫啉和氟啶虫胺腈抗性水平监测与交互抗性分析

为了解我国不同地区棉蚜Aphis gossypii对吡虫啉和氟啶虫胺腈的抗性现状,对代表性棉区棉蚜田间种群进行抗药性监测,同时通过构建具有R81T及V62I单突变和R81T-V62I共同突变的棉蚜烟碱型乙酰胆碱受体(nicotinic acetylcholine receptor,nAChR)蛋白模型,与吡虫啉和氟啶虫胺腈进行分子对接,分析这些突变在吡虫啉和氟啶虫胺腈抗性中的作用,并分析吡虫啉和氟啶虫胺腈之间是否存在交互抗性。结果显示,不同地区棉蚜对吡虫啉产生了高水平抗性,抗性倍数为174.70～56 409.18,对氟啶虫胺腈产生了低至中等水平抗性,抗性倍数为7.35～44.63,说明不同地区的棉蚜对氟啶虫胺腈的敏感度高于吡虫啉,且吡虫啉抗性和氟啶虫胺腈抗性间不存在相关性。R81T、V62I单突变和R81T-V62I共同突变导致吡虫啉与棉蚜nAChR的亲和力降低,对氟啶虫胺腈与棉蚜n AChR的结合无明显影响。R81T及V62I单突变和R81T-V62I共同突变导致棉蚜对吡虫啉产生靶标抗性,但是对氟啶虫胺腈的抗性无明显影响,这些突变不会导致吡虫啉与氟啶虫胺腈产生靶标突变的交互抗性。     

不同冻结速率对脆肉鲩鱼片冻结特性的影响研究

为了研究不同冻结速率对鱼片冻结品质的影响程度、产生原因及其机理,该文以脆肉鲩鱼片为对象,研究了4种不同冻结速率(3.69、2.64、0.60、0.34 cm/h)对鱼片冻结曲线及其品质(理化特性和质构特性)的影响.试验结果表明,脆肉鲩鱼片的冻结点为(-0.6±0.1)℃;随着冻结速率的增加,汁液流失率减少,盐溶蛋白含量的降低率以及Ca2 -ATPase活性的损失率都有不同程度的降低,但冻结过程提高风速则导致干耗增加;与新鲜鱼片相比,速冻样解冻后硬度与耐咀性无变化,而慢冻样解冻后硬度与耐咀性却有所下降;4种冻结速率下解冻样的回复性均有不同程度的下降.综合理化指标和质构特性的检测结果,在注意减少干耗影响的前提下,提高冻结速率有利于保持脆肉鲩鱼片的品质.     

茄子黄萎病菌不同致病力菌株生物学特性的比较

在雅安近郊茄园中,采集黄萎病症状典型的茄株,进行了病原菌的分离鉴定,并研究了病原菌的致病力、生物学特性。结果表明:茄子黄萎病的病原菌为大丽轮枝菌(Verticillium dahliaeKleb),22.5℃为菌丝生长和产孢的最适温度;pH 7时最适菌丝生长,而产孢量的高峰出现在pH 4和pH 8。强致病力菌株在各个温度和pH下的生长、产孢和孢子萌发均大于弱致病力菌株;对碳源的利用以蔗糖较好,氮源以KNO3较好,在相同的营养条件下强弱菌株生长量差异不大,弱致病力菌株的拟菌核的萌发能力和耐热性强于强致病菌株。     

牡荆总黄酮提取工艺优化及其对产气荚膜梭菌抑菌活性研究

【目的】 探究牡荆总黄酮的提取工艺，并探讨牡荆提取物对产气荚膜梭菌的抑菌活性。【方法】 以芦丁作为对照品，采用分光光度法对牡荆中的总黄酮含量进行测定；以总黄酮含量为考察指标，先通过单因素试验研究乙醇浓度、提取时间、提取温度、料液比4个单因素对牡荆总黄酮提取量的影响，确定单因素情况下最佳工艺的水平范围；在单因素试验基础上，通过设计L9（3⁴）正交试验，利用NaNO₂-AL （NO₃）₃-NaOH显色法对牡荆总黄酮含量进行测定，绘制标准曲线，计算回归方程，通过精密度、稳定性、重复性、加样回收率进行方法学考察，验证标准曲线。通过将试验所得数据代入标准曲线，比较得出牡荆总黄酮的最佳制备工艺，并在此基础上通过微量二倍稀释法考察其提取物对产气荚膜梭菌的抗菌活性。【结果】 牡荆总黄酮最佳提取工艺条件为：乙醇浓度60%、提取温度50 ℃、提取时间2.5 h、料液比1：35。在此最优提取条件下，牡荆总黄酮含量最高（43.17 mg/g）。其因素影响顺序为料液比>提取时间>乙醇浓度>提取温度，料液比对牡荆总黄酮含量影响最大。最佳工艺下的牡荆提取物对产气荚膜梭菌的最小抑菌浓度（MIC）值为7.81 μg/mL。【结论】 在乙醇浓度60%、提取温度50 ℃、提取时间2.5 h、料液比1：35的条件下提取的牡荆总黄酮含量最高，所制备提取物对产气荚膜梭菌具有较强的抑菌作用，为生产高质量的牡荆提取物提供了理论依据。     

Image recognition and empirical application of desert plant species based on convolutional neural network

In recent years, deep convolution neural network has exhibited excellent performance in computer vision and has a far-reaching impact. Traditional plant taxonomic identification requires high expertise, which is time-consuming. Most nature reserves have problems such as incomplete species surveys, inaccurate taxonomic identification, and untimely updating of status data. Simple and accurate recognition of plant images can be achieved by applying convolutional neural network technology to explore the best network model. Taking 24 typical desert plant species that are widely distributed in the nature reserves in Xinjiang Uygur Autonomous Region of China as the research objects, this study established an image database and select the optimal network model for the image recognition of desert plant species to provide decision support for fine management in the nature reserves in Xinjiang, such as species investigation and monitoring, by using deep learning. Since desert plant species were not included in the public dataset, the images used in this study were mainly obtained through field shooting and downloaded from the Plant Photo Bank of China (PPBC). After the sorting process and statistical analysis, a total of 2331 plant images were finally collected (2071 images from field collection and 260 images from the PPBC), including 24 plant species belonging to 14 families and 22 genera. A large number of numerical experiments were also carried out to compare a series of 37 convolutional neural network models with good performance, from different perspectives, to find the optimal network model that is most suitable for the image recognition of desert plant species in Xinjiang. The results revealed 24 models with a recognition Accuracy, of greater than 70.000%. Among which, Residual Network X_8GF (RegNetX_8GF) performs the best, with Accuracy, Precision, Recall, and F1 (which refers to the harmonic mean of the Precision and Recall values) values of 78.33%, 77.65%, 69.55%, and 71.26%, respectively. Considering the demand factors of hardware equipment and inference time, Mobile NetworkV2 achieves the best balance among the Accuracy, the number of parameters and the number of floating-point operations. The number of parameters for Mobile Network V2 (MobileNetV2) is 1/16 of RegNetX_8GF, and the number of floating-point operations is 1/24. Our findings can facilitate efficient decision-making for the management of species survey, cataloging, inspection, and monitoring in the nature reserves in Xinjiang, providing a scientific basis for the protection and utilization of natural plant resources.     

Retrospective evaluation of the impact of hypoxemia during thoracic surgery in dogs on outcome: a multicenter analysis of 94 cases

ObjectiveTo investigate the statistical association of severe intraoperative hypoxemia in thoracic surgery with mortality, postoperative hospitalization times and cost of care.Study designRetrospective study.AnimalsDogs that underwent thoracic surgery in three veterinary hospitals between October 1, 2018 and October 1, 2020.MethodsAnesthesia and hospitalization records from 112 dogs were reviewed and 94 cases met inclusion criteria. Recorded data included signalment, disease etiology, pulmonary or extrapulmonary nature of disease, surgical procedure performed, episodes of severe intraoperative hypoxemia defined as a pulse oximetry reading (SpO₂) <90% of 5 minutes or longer duration, survival to discharge, time from extubation to hospital discharge and total invoice cost for clinical visit. Dogs were divided into two groups, those that experienced severe hypoxemia (group A) and those in which SpO₂ reading <90% was not observed throughout the procedure (group B).ResultsGroup A had a greater risk of mortality (odds ratio 10.6, 95% confidence interval 1.9–106.7; p = 0.002), prolonged hospitalization (median 62 hours versus 46 hours; p = 0.035) and more expensive cost of care (median US$10,287 versus $8506; p = 0.056) than group B. No significant difference was found for the type of surgical procedure or pulmonary versus extrapulmonary nature of disease.Conclusions and clinical relevanceSevere intraoperative hypoxemia was statistically associated with an increased risk of mortality and longer postoperative hospitalization times. Although not achieving statistical significance, there was a trend toward increased costs to the client for animals with intraoperative hypoxemia.