Detection of fluoroquinolone resistance level in clinical canine and feline Escherichia coli pathogens using rapid real-time PCR assay

Fluoroquinolones are used to treat infections caused by Escherichia coli in canine and feline veterinary patients, particularly those infecting the urinary tract. The gyrA gene is a primary target causing fluoroquinolone resistance in Gram negative coliforms, with mutations in codons 83 and 87 generally associated with high-level of resistance E. coli clinical isolates. We have developed a fluorescence resonance energy transfer (FRET) quantitative PCR to identify enrofloxacin-resistance in clinical E. coli isolates that carry mutations in codons 83 and 87 of gyrA. This real-time quantitative PCR assay is rapid, economical, and sensitive compared with cultured antimicrobial susceptibility testing. The assay identified as few as four genome copies per reaction from culture and 19 genome copies in urine. For the 70 isolates tested, the sensitivity was 87.5% (95% CI = 75–95.3%) (n = 42/48), specificity was 100% (95% CI = 87.3–100%) (n = 22/22), whereas accuracy was 91.4% (95% CI = 82.3–97%) (n = 64/70). Furthermore, we were able to accurately differentiate between the wild type and mutants E. coli directly from infected canine urine samples (n = 5) within 2 h. These results were confirmed by sequence alignments of the PCR products and comparison with the susceptibility testing. The FRET-PCR assay appears to have promising clinical application as an early diagnostic tool for rapid and sensitive detection and differentiation of the level of fluoroquinolone resistance among clinical E. coli isolates that may facilitate design of the dosing regimen.     

EnMIC2重组减毒沙门氏菌的构建及免疫保护效果研究

成功构建了表达鸡毒害艾美耳球虫(Eimeria necatrix)广东株(GD)微线蛋白-2基因(EnMIC2)的重组减毒鼠伤寒沙门氏菌，在IPTG诱导下获得了EnMIC2的高效表达，SDS-PAGE分析表明，表达产物约占菌体总蛋白的8．6％，分子量大小约为35ku，与抗E．necatrix的高免血清进行Western Blotting，结果为阳性。将重组减毒沙门氏菌以10^8和10^9 CFU／鸡免疫4日龄岭南黄肉鸡，免疫后2周血清中可检测到特异性IgG，3周时抗体水平达到峰值，同时可在肠道检测到特异性IgA的分泌。免疫接种后3周，试验鸡分别经口攻击感染500个E．necatrix(GD)孢子化卵囊，结果显示免疫组与非免疫组有相似的排卵囊曲线；但10^8和10^9CFU免疫组的卵囊总产量分别能降低26．62％和48．92％。     

Rhizosphere effects of <Emphasis Type="Italic">Populus euramericana</Emphasis> Dorskamp on the mobility of Zn,Pb and Cd in contaminated technosols

Purpose

This study aimed at investigating the rhizosphere effects of Populus euramericana Dorskamp on the mobility of Zn, Pb and Cd in contaminated technosols from a former smelting site.

Materials and methods

A rhizobox experiment was conducted with poplars, where the plant stem cuttings were grown in contaminated technosols for 2 months under glasshouse conditions. After plant growth, rhizosphere and bulk soil pore water (SPW) were sampled together. SPW properties such as pH, dissolved organic carbon (DOC) and total dissolved concentrations of Zn, Pb and Cd were determined. The concentrations of Zn, Pb and Cd in plant organs were also determined.

Results and discussion

Rhizosphere SPW pH increased for all studied soils by 0.3 to 0.6 units compared to bulk soils. A significant increase was also observed for DOC concentrations regardless of the soil type or total metal concentrations, which might be attributed to the plant root activity. For all studied soils, the rhizosphere SPW metal concentrations decreased significantly after plant growth compared to bulk soils which might be attributed to the increase in pH and effects of root exudates. Zn, Pb and Cd accumulated in plant organs and the higher metal concentrations were found in plant roots compared to plant shoots.

Conclusions

The restricted transfer of the studied metals to the plant shoots confirms the potential role of this species in the immobilization of these metals. Thus, P. euramericana Dorskamp can be used for phytostabilization of technosols.

     

Safety of human therapeutic morphine vaccine employing Lohmann specific pathogen free eggs

One of the sensitive and standard tests to control the safety of a vaccine is the inoculation of such vaccine to the air pocket of Lohmann specific pathogen free eggs. The aim of this study is to control the safety of morphine vaccine. This study reveals the safety of morphine vaccine by employing Lohmann specific pathogen free embryo eggs. The changeable parameters in this test were: weight of eggs, safety of eggs embryo, vaccine concentration, normal saline and temperature of the incubator. To study, the safety of morphine vaccine, we used 30 eggs (after controlling the safety of eggs and their embryos) which were divided into two groups of control (15 eggs) and test (15 eggs). After weighing the eggs, the eggs under experiment were inoculated with morphine vaccine and the control group was inoculated with physiological solution. Both groups were incubated and weight of the eggs and chickens were determined accordingly. The eggs of each group were controlled by their weights showing healthy, normal growth and evolution. The comparison between the weights of control and experimental groups did not show any significant changes. Exactly growth and evolution of each group were found equally to be balancing for three weeks after injection. Finally all eggs were observed to be safe, alive and in evolutionary form. By comparing the growth and evolution amongst each egg in the group under experiment, after injection, the eggs did not show any adverse reaction after inoculation with therapeutic human morphine vaccine.     

耕作机具能耗模拟研究进展(英文)

耕作机具的能耗模拟研究始于20世纪60年代。近年来,性能强大的计算机应用和先进建模技术与软件的发展,提高了研究人员建模分析和预测不同耕作条件下(如耕作机具所引起的土壤运动、土体破坏分布、作物残茬处理和肥料施用等)机具性能和能耗状况的能力。研究人员使用解析分析、数值模拟和经验法等方法,建立了耕作机具能耗的多种数学模型。该文对耕作机具能耗数学模型进行了系统的概述,总结了已有的研究成果,重点论述了数学模型的分类和特点,模型参数的测定、验证和模型的适用范围,可为耕作机理深入研究和耕作机具优化改进提供参考。     

鸡体内减毒鼠伤寒沙门氏菌的繁殖和免疫反应

初步研究了cya和crp双基因突变减毒鼠伤寒沙门氏菌(Salmonella typhimurium)在鸡体内的繁殖和免疫反应。1、4或7日龄肉鸡分别经口感染10^8或10^9CFU减毒S．typhimurium X4550，接种后3—4周鸡体内特异性细胞和体液免疫达到最高峰。4日龄口服10^9CFu组免疫效果最佳，但1日龄高剂量组表现增重降低及免疫抑制。28日龄每鸡口服攻击10^10CFU强毒S．typhimurium 50333，各免疫组保护率为100％。同时免疫鸡还能全部或部分阻止沙门氏菌在肝脏和脾脏的繁殖。接种后病毒S．typhimurium在泄殖腔的检出时间为4周左右。     

Synthesis of an eco-friendly nanocomposite fertilizer for common bean based on carbon nanoparticles from agricultural waste biochar

The burning of agricultural waste is a major cause of environmental pollution. In this study, we sought to prepare biochar from agricultural waste as a source material for the preparation of carbon nanoparticles (CNPs). Surface morphology, hydrodynamic particle size, and purity and crystallinity of CNPs were extensively investigated using transmission electron microscopy (TEM), zeta sizing, and X-ray diffraction (XRD) spectroscopy, respectively. The CNPs were subsequently immersed in a solution of potassium nitrate (KNO³) to prepare a CNPs/NK nanocomposite (CNPs loaded with nitrogen (N) and potassium (K)) as a nanocomposite fertilizer for common bean (Phaseolus vulgaris L.). The CNPs/NK nanocomposite was sprayed as a foliar fertilizer at 0, 10, 20, 30, and 40 mg L^-1 on common bean plants 25 d after sowing on a farm in Shebin El-Kom, El-Monifia, Egypt. The growth, yield, and quality of common bean were investigated during two successive growing seasons (2017 and 2018). The highest seed yields of 2.04 and 2.01 t ha^-1 and the highest values of growth parameters including plant height of 61.5 and 59.2 cm, number of leaves per plant of 35 and 35, number of flowers per plant of 83.3 and 82.7, and plant fresh weight of 148.7 and 152.8 g plant^-1 were obtained when using the CNPs/NK nanocomposite at a concentration of 20 mg L^-1 during the 2017 and 2018 growing seasons, respectively.     

COVID-19 impacts on the Bangladesh shrimp industry: A sequential survey-based case study from southwestern Bangladesh

Shrimp farming is fundamental to the national economy of Bangladesh, particularly through earning foreign currency. The nationwide lockdown and international cargo restriction jeopardized the sector and breaking its marketing chain. Assessing the degree of farming socio-economic peril from COVID-19 and suggesting early coping strategies and long-term mitigation measures are pressing to build resilience for this food production sector. To collect survey data, two key-informant face-to-face surveys with 51 shrimp farmers and 62 consumers in southwest Bangladesh were accomplished. As national lockdowns restricted access to export markets and movements within the country, farm incomes decreased against rising production costs. To compensate, farmers reduced their workforce (29.4%), but even with the sale of co-cultured finfish still suffered from large drops in revenue (42.8% average profit reduction). Furthermore, we present evidence that shrimp farmers should consider diversification of aquaculture product type as co-culture of additional shrimp species was a poor mitigation strategy against large market price fluctuations. Product price reductions were passed on to the consumer, who enjoyed falling product prices including more expensive shrimp products, but the markup for nearly all aquaculture products increased. The current jeopardy and consequences of shrimp farming future are discussed, including coping strategies to help policymakers in building resilience against future uncertainties.