Clinical Characteristics Associated with Borrelia burgdorferi Sensu Lato Skin Culture Results in Patients with Erythema Migrans

Clinical characteristics associated with isolation of Borrelia burgdorferi sensu lato from skin have not been fully evaluated. To gain insight into predictors for a positive EM skin culture, we compared basic demographic, epidemiologic, and clinical data in 608 culture-proven and 501 culture-negative adult patients with solitary EM. A positive Borrelia spp. skin culture was associated with older age, a time interval of >2 days between tick bite and onset of the skin lesion, EM ≥5 cm in diameter, and location of the lesion on the extremities, whereas several other characteristics used as clinical case definition criteria for the diagnosis of EM (such as tick bite at the site of later EM, information on expansion of the skin lesion, central clearing) were not. A patient with a 15-cm EM lesion had almost 3-fold greater odds for a positive skin culture than patients with a 5-cm lesion. Patients with a free time interval between the tick bite and onset of EM had the same probability of a positive skin culture as those who did not recall a tick bite (OR=1.02); however, the two groups had >3-fold greater odds for EM positivity than patients who reported a tick bite with no interval between the bite and onset of the lesion. In conclusion, several yet not all clinical characteristics used in EM case definitions were associated with positive Borrelia spp. skin culture. The findings are limited to European patients with solitary EM caused predominantly by B. afzelii but may not be valid for other situations.     

The Effects of Catalyst Layer Deposition Methodology on Electrode Performance

The catalyst layer of the cathode is arguably the most critical component of low‐temperature fuel cells and carbon dioxide (CO₂) electrolysis cells because their performance is typically limited by slow oxygen (O₂) and CO₂ reduction kinetics. While significant efforts have focused on developing cathode catalysts with improved activity and stability, fewer efforts have focused on engineering the catalyst layer structure to maximize catalyst utilization and overall electrode and system performance. Here, we study the performance of cathodes for O₂ reduction and CO₂ reduction as a function of three common catalyst layer preparation methods: hand‐painting, air‐brushing, and screen‐printing. We employed ex‐situ X‐ray micro‐computed tomography (MicroCT) to visualize the catalyst layer structure and established data processing procedures to quantify catalyst uniformity. By coupling structural analysis with in‐situ electrochemical characterization, we directly correlate variation in catalyst layer morphology to electrode performance. MicroCT and SEM analyses indicate that, as expected, more uniform catalyst distribution and less particle agglomeration, lead to better performance. Most importantly, the analyses reported here allow for the observed differences over a large geometric volume as a function of preparation methods to be quantified and explained for the first time. Depositing catalyst layers via a fully‐automated air‐brushing method led to a 56% improvement in fuel cell performance and a significant reduction in electrode‐to‐electrode variability. Furthermore, air‐brushing catalyst layers for CO₂ reduction led to a 3‐fold increase in partial CO current density and enhanced product selectivity (94% CO) at similar cathode potential but a 10‐fold decrease in catalyst loading as compared to previous reports.     

甘蔗鞭黑粉菌侵染甘蔗的早期可视化观察

【目的】甘蔗鞭黑粉菌(Sporisorium scitamineum)引起的甘蔗黑穗病是我国甘蔗生产重要的病害。示踪甘蔗鞭黑粉菌侵染甘蔗的过程将有助于揭示其致病性和甘蔗抗黑穗病机制,为抗病品种的选育以及黑穗病的防治奠定基础。【方法】利用农杆菌介导的遗传转化技术对甘蔗鞭黑粉菌进行黄色荧光标记,对转化子进行配合及致病力检测,将标记菌株接种甘蔗感病品种ROC22及抗病品种中蔗1号、中蔗6号和中蔗9号并进行早期可视化观察。【结果】组成型表达的eYFP不影响标记菌株的配合及致病能力,而且黄色荧光性状能通过冬孢子稳定遗传。激光共聚焦显微观察表明,注射接种病原菌第5天,在感病品种ROC22的生长点已可见荧光菌丝及少量聚集状菌丝体,在抗病品种中蔗1号、中蔗6号和中蔗9号中可见少量单一丝状菌丝,无聚集状菌丝体。接种后35 d,在ROC22中可见大量聚集状菌丝体,但在中蔗品种中的聚集状菌丝体明显较少,而以中蔗1号最少。【结论】成功构建了甘蔗鞭黑粉菌侵染甘蔗的荧光示踪系统,并发现中蔗系列品种存在抑制甘蔗鞭黑粉菌菌丝体在细胞间扩展的机制。     

日粮添加复合饲用益生菌对肉牛生长性能及肠道微生物的影响

[目的] 为研究添加饲用益生菌对肉牛生长性能、血液生理生化指标及肠道微生物区系的影响。[方法] 在青海地区选取西门塔尔牛与荷斯坦牛的杂交1代18头,按每组平均体重相近的原则随机分为2组,每组9头,试验组饮食添加地衣芽孢杆菌、枯草芽孢杆菌和酿酒酵母的复合饲用益生菌。[结果] 试验结果表明：试验组显著地提高了胸围日增长量（P=0.029）;试验组皮质醇浓度显著（P<0.05）高于对照组,高密度胆固醇脂蛋白、低密度胆固醇脂蛋白与总胆固醇浓度显著（P<0.05）低于对照组;进一步分析肠道微生物发现,两组之间Alpha多样性没有显著差异（P>0.05）,Beta多样性差异显著（P<0.05）;Tenericutes、Alistipes和Ruminococcaceae的相对丰度在试验组显著高于对照组（P<0.05）,而Alloprevotella相对丰度显著低于对照组（P<0.05）;检测到的芽孢杆菌种没有显著的差异,有趣的是,试验组降低了肠道中的大肠杆菌丰度。[结论] 综上,饲喂复合饲用益生菌能够有效降低血清胆固醇的合成、抑制有害微生物的繁殖。该研究为益生菌干预肉牛健康养殖提供了理论依据。     

Entrapment of Ovalbumin into Liposomes—Factors Affecting Entrapment Efficiency,Liposome Size,and Zeta Potential

Various amounts of Ovalbumin (OVA) were encapsulated into positively and negatively charged multilamellar liposomes, with the aim to investigate the entrapment efficiency in different buffers and to study their effects on the liposome size and zeta potential. Results showed that the entrapment efficiency of OVA in anionic liposomes was the same in 10 mM Phosphate Buffer (PB) as in Phosphate-Buffered Saline (PBS; PB?+?0.15 M NaCl). Also, liposome size was approximately 1200 nm for all anionic liposomes incorporating OVA. The entrapment efficiency of OVA in cationic liposomes was highly dependent on ionic strength. The size of cationic liposomes was approximately 1200 nm in PBS, regardless of protein content, but increased with the amount of the incorporated protein in PB. Aggregation of cationic liposomes in PB was observed when the mass of the protein was 2.5 mg or greater. The zeta potential of anionic liposomes was negative and of cationic liposomes positive in the whole range of protein mass tested. These results show how different compositions of lipid and aqueous phases can be used to vary the entrapment efficiency, liposome size, and zeta potential—the factors that are of great importance for the use of liposomes as drug carriers.     

Analysis of B-Class Genes NAP3L3 and NAP3L4 in Narcissus tazetta var. chinensis

Very few flower organ identity genes have been characterized in Chinese narcissus (Narcissus tazetta var. chinensis), which has petaloid sepals. Here, we report the cloning of two full-length B-class genes, namely NAP3L3 and NAP3L4, that are orthologs of the DEFICIENS lineage. Both genes are highly expressed in the second whorl of the perianth and in the stamens. NAP3L4 is also expressed strongly in the ovule. The functions of these two genes were further analyzed using transgenic plants. Ectopic expression of either gene in Arabidopsis gave no obvious floral organ transformation phenotypes. In yeast two-hybrid assays, NAP3L3 and NAP3L4 failed to homodimerize and interacted weakly with each other. The data suggest that these two genes might not be involved in the formation of petaloid sepals. Isolation and functional analysis of other B-class paralogs should be conducted to fully understand petaloid tepal development in Chinese narcissus.     

Aluminum induces low phosphate adaptive responses and modulates primary and lateral root growth by differentially affecting auxin signaling in Arabidopsis seedlings

Aims

The aims of this work were to investigate the aluminum (Al) and phosphate (P) interactions in the regulation of root system architecture of Arabidopsis thaliana seedlings and the contribution of auxin signaling in primary and lateral root growth in response to Al toxicity.

Methods

Detailed analyses of root system architecture and cell division were performed in Arabidopsis WT seedlings and in low phosphorus insensitive mutants lpi1-3 and lpr1-1 lpr2-1 in response to Al. Expression studies of P-deficiency regulated phosphate transporter AtPT2 were also conducted. The role of auxin as a mediator of root morphogenetic changes by Al was evaluated by using the auxin-signaling mutants tir1, tir1 afb2 afb3, and arf7 arf19.

Results

Al inhibited primary root growth by affecting cell cycle progression and causing differentiation of cells in the root meristem. These effects were reduced in low phosphorus insensitive lpi1-3 and low phosphate resistant lpr1-1 lpr2-1 Arabidopsis mutants. Al also activated the expression of the low phosphate-induced P transporter AtPT2 in roots. Lateral root formation by Al decreased in tir1 afb2 afb3 while arf7 arf19 mutants were highly resistant to Al in both primary root inhibition and lateral root induction.

Conclusions

Our results suggest that lateral root formation in response to Al toxicity and P deficiency may involve common signaling mechanisms, while a pathway involving ARF7 and ARF19 is important for primary root growth inhibition by Al.     

湖南工程学院生物工程专业实践 教学模式创新与实践

分析生物工程专业人才需求的现状与发展前景,构建了以社会需求为导向,以实践课程体系为载体,以能力培养为主线,以学生科技创新活动和教师科研为驱动,项目研究与能力培养相结合的创新实践教学模式.实践表明,创新实践教学模式极大提高了学生的学习兴趣和教师的工作热情.     

Identification of the infectious source of an unusual outbreak of histoplasmosis,in a hotel in Acapulco,state of Guerrero,Mexico

Three isolates of Histoplasma capsulatum were identified from mice lung, liver, and spleen inoculated with soil samples of the X hotel’s ornamental potted plants that had been fertilized with organic material known as compost. The presence of H. capsulatum in the original compost was detected using the dot-enzyme-linked immunosorbent assay. Nested-PCR, using a specific protein Hcp100 coding gene sequence, confirmed the fungal identification associated with an unusual histoplasmosis outbreak in Acapulco. Although, diversity between the H. capsulatum isolate from the hotel and some clinical isolates from Guerrero (positive controls) was observed using random amplification of polymorphic DNA based-PCR, sequence analyses of H-anti and ole fragment genes revealed a high homology (92–99%) between them.