A Modified EPA Method 1623 that Uses Tangential Flow Hollow-fiber Ultrafiltration and Heat Dissociation Steps to Detect Waterborne Cryptosporidium and Giardia spp.

Cryptosporidium and Giardia species are two of the most prevalent protozoa that cause waterborne diarrheal disease outbreaks worldwide. To better characterize the prevalence of these pathogens, EPA Method 1623 was developed and used to monitor levels of these organisms in US drinking water supplies ¹². The method has three main parts; the first is the sample concentration in which at least 10 L of raw surface water is filtered. The organisms and trapped debris are then eluted from the filter and centrifuged to further concentrate the sample. The second part of the method uses an immunomagnetic separation procedure where the concentrated water sample is applied to immunomagnetic beads that specifically bind to the Cryptosporidium oocysts and Giardia cysts allowing for specific removal of the parasites from the concentrated debris. These (oo)cysts are then detached from the magnetic beads by an acid dissociation procedure. The final part of the method is the immunofluorescence staining and enumeration where (oo)cysts are applied to a slide, stained, and enumerated by microscopy.Method 1623 has four listed sample concentration systems to capture Cryptosporidium oocysts and Giardia cysts in water: Envirochek filters (Pall Corporation, Ann Arbor, MI), Envirochek HV filters (Pall Corporation), Filta-Max filters (IDEXX, Westbrook, MA), or Continuous Flow Centrifugation (Haemonetics, Braintree, MA). However, Cryptosporidium and Giardia (oo)cyst recoveries have varied greatly depending on the source water matrix and filters used^1,14. A new tangential flow hollow-fiber ultrafiltration (HFUF) system has recently been shown to be more efficient and more robust at recovering Cryptosporidium oocystsand Giardia cysts from various water matrices; moreover, it is less expensive than other capsule filter options and can concentrate multiple pathogens simultaneously^{1-3,5-8,10,11}. In addition, previous studies by Hill and colleagues demonstrated that the HFUF significantly improved Cryptosporidium oocysts recoveries when directly compared with the Envirochek HV filters⁴. Additional modifications to the current methods have also been reported to improve method performance. Replacing the acid dissociation procedure with heat dissociation was shown to be more effective at separating Cryptosporidium from the magnetic beads in some matrices^9,13 .This protocol describes a modified Method 1623 that uses the new HFUF filtration system with the heat dissociation step. The use of HFUF with this modified Method is a less expensive alternative to current EPA Method 1623 filtration options and provides more flexibility by allowing the concentration of multiple organisms.     

Improved enrichment and proteomic identification of outer membrane proteins from a Gram-negative bacterium: focus on Caulobacter crescentus

Efforts to characterize proteins found in the outer membrane (OM) of Gram-negative bacteria have been steadily increasing due to the promise of expanding our understanding of fundamental bacterial processes such as cell adhesion or cell wall biogenesis as well as the promise of finding potential vaccine- or drug-targets for virulent bacteria. We have developed a mass spectrometry-compatible experimental strategy that resulted in increased coverage of the OM proteome of a model organism, Caulobacter crescentus. The specificity of the OM enrichment step was improved by using detergent solubilization of the protein pellet, low-density cell culture conditions, and a surface-layer deficient cell line. Additionally, efficient gel-assisted digestion, high-resolution RP/RP-MS/MS, and rigorous bioinformatic analysis led to the identification of 234 proteins using strict identification criteria (≥ two unique peptides per protein; peptide false discovery rate <2%). Eighty-four of the detected proteins were predicted to localize to the OM or extracellular space. These results represent ~70% coverage of the predicted OM/extracellular proteome of C. crescentus. This analytical approach, which considers important experimental variables not previously explored in published OM protein studies, can be applied to other OM proteomic endeavors "as is" or with slight modification and should improve the large-scale study of this especially challenging subproteome.     

制备精原干细胞滋养层细胞条件的优化

目的:优化精原干细胞培养滋养层细胞的制备条件。方法:首先根据文献资料报道和实践经验确定丝裂霉素C作用STO细胞的浓度范围和时间范围,利用双因素优选法缩短丝裂霉素C处理STO细胞的试验范围。然后采用MTT检测法确定丝裂霉素C处理STO细胞的最佳浓度和时间。结果:滋养层细胞处理后不经过冷冻保存的情况下,17.64μg/ml 2 h处理条件的STO细胞在培养14天内细胞数量基本保持稳定,其它处理条件的细胞数量均有所增加;经冷冻保存的情况下,14.72μg/ml 2 h处理条件的STO细胞在培养14天内细胞数量基本保持稳定,其它处理条件的细胞数目均有所降低。结论:滋养层细胞处理后不经过冷冻保存的情况下,17.64μg/ml 2 h的处理条件是丝裂霉素C处理STO细胞的最佳条件;经冷冻保存的情况下,14.72μg/ml 2 h的处理条件是丝裂霉素C处理STO细胞的最佳条件。     

外阴诱发电位及其应用

诱发电位（EP）是继脑电图和肌电图之后临床神经电生理的第三大进展,在检测神经系统的状态和变化上有重要意义,常常用来协助确定神经系统的可疑病变,检出亚临床病灶,帮助病损定位,监护感觉系统的功能状态。其中,视觉、听觉和部分体感诱发电位已得到广泛应用。本文介绍了外阴诱发电位的相关原理及其应用等。     

Saddle-Point Approximations,Integrodifference Equations,and Invasions

Invasion, the growth in numbers and spatial spread of a population over time, is a fundamental process in ecology. Governments and businesses expend vast sums to prevent and control invasions of pests and pestilences and to promote invasions of endangered species and biological control agents. Many mathematical models of biological invasions use nonlinear integrodifference equations to describe the growth and dispersal processes and to predict the speed of invasion fronts. Linear models have received less attention, perhaps because they are difficult to simulate for large times. In this paper, we use the saddle-point method, alias the method of steepest descent, to derive asymptotic approximations for the solutions of linear integrodifference equations. We work through five examples, for Gaussian, Laplace, and uniform dispersal kernels in one dimension and for asymmetric Gaussian and radially symmetric Laplace kernels in two dimensions. Our approximations are extremely close to the exact solutions, even for intermediate times. We also employ an empirical saddle-point approximation to predict densities using dispersal data. We use our approximations to examine the effects of censored dispersal data on estimates of invasion speed and population density.     

R法遗传参数估值置信区间的计算方法和重复估计次数的研究

探讨R法遗传参数估值置信区间的计算方法和重复估计次数(NORE)对参数估值的影响,利用4种模型通过模拟产生数据集。基础群中公、母畜数分别为200和2000头,BLUP育种值选择5个世代。利用多变量乘法迭代(MMI)法,结合先决条件的共扼梯度(PCG)法求解混合模型方程组估计方差组分。用经典方法、Box-Cox变换后的经典方法和自助法计算参数估值的均数、标准误和置信区间。结果表明,重复估计次数较多时,3种方法均可;重复估计次数较少时,建议使用自助法。简单模型下需要较少的重复估计,但对于复杂模型则需要较多的重复估计。随模型中随机效应数的增加,直接遗传力高估。随着PCG和MMI轮次的增大,参数估值表现出低估的趋势。     

植原体DNA提取方法的改良

在总结多种植原体DNA提取方法的基础上 ,发展了一种提取植原体DNA新方法。用此方法提取的DNA经琼脂糖凝胶电泳检测到大于 15kb的DNA主带 ,基本无DNA碎带 ,不用RNase处理 ,也无RNA干扰 ,OD2 60 / 2 80 值显示产物纯度较高 ,无需任何处理 ,即可以作为模板扩增     

Tamarindus indica L. leaf is a source of allelopathic substance

The allelopathic potential of the Tamarindus indica L. leaf was investigated through bioassay guided studies using several weed and edible crop species. Both radicle and hypocotyl growth of all the plant species tested was strongly inhibited by the tamarind leaf using a sandwich method. The growth of weed species was reduced more than that of edible crop species. Among the weed species, barnyard grass followed by white clover, and in the edible crop species, lettuce followed by radish ranked top in terms of growth inhibition. Different concentrations of tamarind leaf crude water-soluble extract exhibited a strong inhibition in all the plant species tested and, by contrast, the magnitude of inhibition in the weed species was higher than in edible crop species and ranged from 30–75%. The 10% concentration of the tamarind leaf crude water-soluble extract was most potent against growth of seedlings. The concentrations of the nutrient components were linearly correlated with an increase in the concentration of tamarind leaf crude water-soluble extract. No significant changes in either pH or EC were found in the variations of different concentrations of tamarind leaf crude water-soluble extracts. As compared to control, growth of both radicle and hypocotyl in weed (barnyard grass and white clover) and in edible crop (lettuce and radish) species were significantly reduced when blended tamarind leaves at different concentrations were incorporated into the growth medium. The inhibitory magnitude increased with an increase in the concentration of the tamarind leaf. In terms of growth inhibition, among these tested plants, weed species particularly barnyard grass were most sensitive to the allelochemicals exuded from blended tamarind leaves. When the blended tamarind leaves were removed from the growth medium, all the seedlings grew quickly and the percentage of recovery was between 76–97% of the corresponding controls. Reduction in the fresh and dry weight of these 4 plant species was observed under the experimental conditions, and ranged between 33–42% and 40–53% in the radicle and hypocotyl, respectively. The fresh and dry weight, and total chlorophyll content declined significantly in the incorporated tamarind leaf treatments. Compared to the control, the highest drop in the chlorophyll content of 60% in barnyard grass was observed with the 10% concentration of the leaf treatment. These results clearly indicate that the tamarind leaf contains one or more strong biologically active allelochemical(s) that function as true growth regulator(s) and is involved in plant growth regulation, particularly in weed species.     

链霉素抗性突变--纳他霉素高产菌株的选育研究

应用链霉素抗性筛选法,将经过紫外线诱变处理的纳他霉素生产菌——褐黄孢链霉菌(Streptomyces gilvosporeus)ATC13326的孢子涂布在含有链霉素最小抑制浓度(0．6μg／mL)的培养基平板上,获得了122株链霉素抗性突变株。其中纳他霉素产量高于出发菌株的有13株,产量阳性效率达到10．6％,同时获得了产抗生素能力为出发菌株1．46倍的突变株SG-56。     

An Ecosystem Health Index for a large and variable river basin: Methodology,challenges and continuous improvement in Queensland’s Fitzroy Basin

Report cards are an increasingly popular method for summarising and communicating relative environmental performance and ecosystem health, including in aquatic environments. They are usually underpinned by an Ecosystem Health Index (EHI) that combines various individual indicators to produce an overall ecosystem health “score”. As a result of public water quality concerns, an integrated means of monitoring and reporting on aquatic ecosystem health was needed for the Fitzroy Basin in central Queensland, Australia. The Fitzroy Partnership for River Health was formed to address this need, and developed an EHI and report card for the Basin using existing monitoring data collected from various third parties including regulated companies operations and government. At 142,000 square kilometres, the Fitzroy Basin is the largest catchment draining to the World Heritage Listed Great Barrier Reef. The Fitzroy Basin provides an example of how to deliver an effective aquatic ecosystem health reporting system in a large and complex river basin. We describe the methodology used to develop an adaptive EHI for the Fitzroy Basin that addresses variability, complexity and scale issues associated with reporting across large areas. As well, we report how to manage the design and reporting stages given limitations in data collection and scientific understanding.