柑橘黄龙病菌CpaB基因的原核表达和抗体制备

柑橘黄龙病菌CpaB基因编码一种菌毛组装蛋白(Flp pilus assemble protein),前期研究已经证实该蛋白具有外分泌性.在本研究中,首先构建pET30a-CpaB重组载体,然后将其转化BL21(DE3)感受态细胞,重组菌在37℃,0.2 mmol·L^(-1) IPTG诱导下,CpaB蛋白可被成功诱导表达,经过Ni-NTA亲和柱纯化后,获得纯度较高的CpaB重组蛋白,分子量为28.2 kDa,以其为抗原,免疫新西兰大白兔,制备多克隆抗血清;采用Western blot对多抗血清的特异性进行分析,结果显示该多抗能特异性结合纯化的CpaB蛋白;进一步使用制备好的CpaB抗血清对感染黄龙病和健康的柑橘样品进行DTBIA检测,具有较好的区分度.这些研究结果为柑橘黄龙病快速检测体系的建立提供理论参考.

Molecular Detection of Carbapenemase Genes in Extensive Drug Resistant Acinetobacter baumannii Clinical Isolates from ICU Patients, Khartoum

Background: The emergence of carbapenemase producing Acinetobacter baumannii is increasingly reported nowadays and constitutes a major problem to the intensive care unit (ICU) patients with notable extensive-drug resistance ability. The study investigates carbapenemase producing A. baumannii strains exhibiting an extensively drug-resistant (XDR) phenotype, isolated from ICU patients in Khartoum. Methods: A total of 100 nonduplicate Gram-negative coccobacilli strains were obtained from microbiology laboratory of ICU patients’ clinical isolates. Molecular identification of A. baumannii was performed by targeting 16S rRNA gene using specifically designed primers. Then, XDR strains were determined by susceptibility testing (disc diffusion). For detection of carbapenemase genes Polymerase chain reaction (PCR) was carried out. Result: Of 100 ICU clinical isolates, 38 (38.0%) was confirmed A. baumannii strains, those strains showed 100% carbapenem resistance and 60.5% extensive drug resistance to the antibiotics tested. The frequency of carbapenemase producer was 57.9% (22/38) of carbapenem resistance A. baumannii (CRAB). The most common carbapenemase associated with resistance was blaOXA gene followed by blaNDM and blaGES A. baumannii isolates. The co-occurrence of blaOXA-48-like and blaNDM, blaOXA-23-like and blaOXA-51, and blaNDM-1 and blaOXA-51 was detected in 22.7%, 18.2% strains and 4.5% respectively. A unique characteristic of our findings was the coharbouring of the genes blaNDM-1, blaOXA-23-like, blaOXA-51 and blaOXA-143 in 9.1% strains (2/22), and this was the first report in the Khartoum city, Sudan. Conclusion: We have demonstrated for the first time a high prevalence of XDR-carbapenemase producing A. baumannii clinical isolates from ICU patients in Khartoum. Also an emergent blaOXA-143 was reported as High-Risk Clones. This highlights the routine mentoring of XDR-carbapenemase producing A. baumannii to avoid clone dissemination in our region hospitals.

SC-Net:用于重叠染色体分割的上下文信息跳跃连接网络

目的染色体核型分析从细胞分裂中期图像中分离和分类染色体,是遗传疾病诊断广泛采用的方法,其中形态多样的重叠染色体簇的分割,依赖于准确的边界等细节特征。为此,本文融合目标的上下文信息,构建了一种两阶段的重叠染色体分割模型SC-Net(skip connection network)。方法首先,在语义分割基线模型U-Net++中增加混合池化模块捕获重叠染色体的局部上下文信息,在解码器网络中并联上下文融合模块和上下文先验辅助分支,增强通道和空间上的全局上下文信息。其次,利用已标注样本的类别先验信息生成真实亲和矩阵,加入训练过程以有效区分重叠染色体图像中易混淆的空间信息。最后,通过染色体实例重建算法对重叠与非重叠区域的元素迭代进行配对,拼接形成单条染色体。结果在公开的ChromSeg(chromosome segmentation)数据集上进行实验,结果表明SC-Net分割出的重叠染色体区域交并比值为83.5%,与对比算法中的较优算法相比性能提升2.7%。结论本文构建的重叠染色体分割模型通过融合上下文信息,能更有效地解决形态多样的重叠染色体簇的分割问题,相比对比方法可以得到更精细和准确的结果。