Bacterial Exofactors Modulate Biofilm Growth and Resistivity to Antimicrobial Drugs

Some bacteria have the ability to co-exist, proliferate and survive in a multicellular community, biofilm. Each participating bacteria can form its colonies and encases itself by a self-produced insoluble extracellular matrix substance (EPS). Microcolonies within biofilm are held together by interactions and bonding of the substances present in the EPS with their separation from the water channels. Similar to insoluble EPS, bacterial microcolonies release soluble exofactors that have direct impacts on the survivability, growth and antibacterial resistivity of other microcolonies made of single- or multi-species bacteria in the same biofilm. How the exofactors of microcolonies of one-type bacteria impact on microcolonies of other-type bacteria is still unclear. We studied about the role of exofactors released from Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa, which are common biofilm-forming pathogenic bacteria. Exofactors facilitate to transform the microenvironment where bacteria can acquire alternative lifestyle with a long survival period and resistivity to certain antimicrobial drugs.

Financial Statement Fraud: Lessons Learned from Selected U.S. Legal Cases in the past Twenty Years

The researcher analysed selected U.S.court cases of financial statement fraud from the past twenty years and concluded:(1)U.S.laws used to prosecute financial statement fraudsters include the Securities Act,Securities Exchange Act,S.E.C.Rule 10b-5,Investment Advisers Act,Private Securities Litigation Reform Act,and the Sarbanes-Oxley Act;(2)financial statement fraud schemes included use of unconsolidated special-purpose entities to conceal debt,improper revenue recognition in leasing of bandwidth in the telecom industry,improper accounting for goodwill in a merger,failure to write off a large amount of bad receivables,excessive recognition of revenue in bundled leases in the photocopier industry,use of loss contingency reserves to inflate current income,use of fictitious revenue to overstate earnings,and capitalising a project’s operating expenses to hide cost overruns;(3)to be liable for financial statement fraud,a corporate officer must have knowledge;and(4)employees discharged for reporting financial statement fraud may sue under the Sarbanes-Oxley Act.

A New Technique for Use in Culturing Prokaryotes Comprising the Mouse Intestinal Microbiome

The microbiome has a profound impact on host fitness. pH, oxygen, nutrients, or other factors such as food or pharmaceuticals, subject the microbiome to variations in the gastrointestinal tract. This variation is a cause for concern given dysbiosis of the microbiome is correlated with various disease states. Currently, much research relies on model organisms to study microbial communities since intact microbiomes are challenging to utilize. The objective of this study is to culture an explanted colon microbiome of 4 Balb/c mice to develop an in vitro tool for future microbiome studies. We cultured homogenates of the distal colons of 4 mice in trans-well culture dishes. These dishes were incubated for 24 hours in two different oxygen concentration levels and the pH was compared before and after incubation of the cultures. To analyze the integrity of the microbiome, we utilized massively paralleled DNA sequencing with 16S metagenomics to characterize fecal and colon samples to speculate whether future studies may utilize feces in constructing an in vitro microbial community to spare animal lives. We found that pH and familial relationships had a profound impact on community structure while oxygen did not have a significant influence. The feces and the colon were similar in community profiles, which lends credence to utilizing feces in future studies. The gut microbiome is of great interest and great importance for studies in a variety of different diseases. Many laboratories do not have access to germ-free mice, which is one optimal way to study mammalian microbiomes, but this technique allowed for the in vitro culturing of a majority of the prokaryotes isolated from the colons of mice. This may allow an alternative to study the interactions of this very diverse population of microorganisms without the need for germ-free conditions.

Relationships Between Permeability and Erodibility of Cultivated Acrisols and Cambisols in Subtropical China

The relationships between soil erodibility factor （K） and soil saturated permeability （gfs） for cultivated Acrisols derived from Quaternary red clay and Cambisols derived from red sandstone were studied and quantified using a rainfall simulator and Guelph permeameter in a hilly area of subtropical China. A negative correlation existed between Kfs of the topsoil （0-5 cm） and K. The empirical expression K ≈ α × Kfs^-b＋c, where a, b and c are the structural coefficients related to soil properties, such as soil type, soil parent material, organic matter, pH and mechanical composition, best described the relationship between soil saturated permeability and soil erodibility.

Simulation of Hail and Soil Type Effects on Crop Yield Losses in Kansas,USA

Computer simulation was used for predictive analysis of the effects of weather and soil type on crop yield in the U.S. crop insurance program. The Environmental Policy Integrated Climate （EPIC） model was modified to include hail weather events, which completed the modifications necessary to simulate the four most frequent causes of crop yield loss （hail, excessive wet, excessive cold, and excessive dry） associated with soil type in Kansas, USA. At the region level, per hectare yields were simulated for corn, wheat, soybean, and sorghum. We concluded that it was possible to predict crop yields through computer simulation with greater than 93% accuracy. The hail damage model test indicated EPIC could predict hail-soil-induced yield losses reasonably well （R^2 〉 0.6）. The investigation of soil type influence on dryland sorghum and wheat production indicated that Wymore silty clay loam soil and Kenorna silt loam produced the highest sorghum yields statistically; Kuma silt loam, Roxbury silt loam, Crete silty clay loam, and Woodson silt soils produced the second highest sorghum yields statistically; and Richfiled silt loam, Wells loam, and Canadian sandy loam produced the lowest sorghum yields. By contrast, wheat production showed less sensitivity to soil type variation. The less sensitive response of wheat yields to the soil type could be largely due to the unconsidered small-scale variability of soil features.

Impact of Manure Storage Time and Temperature on Microbial Composition and Stable Fly (Diptera: Muscidae) Development

Samples are often frozen for preservation until needed for use. It has been a common practice to store fresh dairy manure in the freezer until needed for fly development studies. However, conflicting data have suggested that freezer temperature and duration of manure may impact fly development studies, and it is likely due to the change in microbial comminutes due to the freezer conditions. In this study manure storage conditions were assessed to ascertain how temperatures impact stable fly, Stomoxys calcitrans L., survival to pupation and determine which bacterial populations impacted fly development using massively-parallel sequencing and 16S metagenomic analysis. Stable fly survival to pupation was greater in manure that was stored warm (27?C) or frozen (-20?C or -80?C) for 24 days as compared to fresh manure samples. Refrigeration (4?C) of the manure for 24 days did not affect fly development and slightly decreased the pupal weights. Over 80 bacterial families were detected by sequencing allowing for a more thorough assessment of changes in bacterial populations. Only minor shifts were observed in bacterial family composition in the manure when refrigerated or frozen for 24 days, but significant population changes were observed when the manure was incubated for 24 days at 27?C. Since it is the temperature and incubation time that yielded the greatest pupation rate, it is hypothesized that the manure microbial community impacts the growth and development of stable flies. This study has determined suggested freezer conditions for the best storage of manure samples to maintain bacterial diversity and retain the closest bacterial populations to freshly collected manure. Although untouched, aged (20 days) manure is best to use to assess fly development, it is not always feasible in laboratory experimentations. This study demonstrates the importance of preservation techniques on manure samples, which could also confer to storage of other biological specimens that contain resident microbes.

Quantitative Methods for Comparing Different Polyline Stream Network Models

Two techniques for exploring relative horizontal accuracy of complex linear spatial features are described and sample source code (pseudo code) is presented for this purpose. The first technique, relative sinuosity, is presented as a measure of the complexity or detail of a polyline network in comparison to a reference network. We term the second technique longitudinal root mean squared error (LRMSE) and present it as a means for quantitatively assessing the horizontal variance between two polyline data sets representing digitized (reference) and derived stream and river networks. Both relative sinuosity and LRMSE are shown to be suitable measures of horizontal stream network accuracy for assessing quality and variation in linear features. Both techniques have been used in two recent investigations involving extraction of hydrographic features from LiDAR elevation data. One confirmed that, with the greatly increased resolution of LiDAR data, smaller cell sizes yielded better stream network delineations, based on sinuosity and LRMSE, when using LiDAR-derived DEMs. The other demonstrated a new method of delineating stream channels directly from LiDAR point clouds, without the intermediate step of deriving a DEM, showing that the direct delineation from LiDAR point clouds yielded an excellent and much better match, as indicated by the LRMSE.

Comparative Assessment of Growth and Gene Regulation between 4 Serotypes of <i>Streptococcus pneumoniae</i>in Broth and Cell Culture

Streptococcus pneumoniae is a medically important pathogen capable of causing human infections of pneumonia, bacteremia, otitis media, and meningitis. Although there are vaccinations available, infections with S. pneumoniae still remains a global problem. S. pneumoniae is a highly adaptable bacterial species with numerous serotypes based on capsular polysaccharides. The different serotypes vary in their ability to colonize and causing pathology. Here we compared the regulation of five different virulence factors from four common serotypes of S. pneumoniae that vary in their carriage, morbidity, and mortality rates in the human population using two different in vitro methods, broth and cell culture. We determine that there is variation of virulence factor gene regulation within a serotype using two different culture methods, and variation between the serotypes in the same culture condition. The regulation of genes appeared to have a correlation with the ability of the various serotypes to grow in broth culture, adhere to cultured lung cells, and invade the cultured lung cells, as serotypes that shared similar regulation of virulence factors tended to behave similarly in culture. Many studies with S. pneumoniae rely on the use of one selected serotype, but since there is a wide variation in the growth and regulatory mechanisms of these bacteria. As demonstrated here, future studies should utilize more strains in models before concluding mechanisms of pathobiology.

Empirical evidence for estimation of subsurface settlement caused by tunneling in sand

Tunneling is vital for augmenting urban infrastructure systems in big cities.However,the ground movement or settlement induced by tunneling can cause significant damage to the surrounding buildings,bridges,roadways,pipelines,and so on.Several theoretical and empirical methods have been proposed to estimate the settlement trough at the ground surface caused by tunneling.Subsurface settlement caused by tunneling in clay has been investigated extensively to evaluate the safety of pipelines and foundations above tunnels based on the assumption of a constant volume of the settlement trough along the depth.However,subsurface settlement induced by tunneling in sand has not been understood well due to the change of volume of settlement trough along the depth.Even though an empirical method was developed by the author based on lab-scale model test results,it has not been validated using observational data from case histories.In this study,three case histories from the literature were used to verify the effectiveness of the aforementioned empirical method for estimating the subsurface settlement caused by tunneling in sand.The comparison of the calculated results and measurements from the case histories demonstrates that the empirical method is effective to predict the subsurface settlement caused by tunneling in sand.

Invasion reproductive numbers for periodic epidemic models

There are many cases within epidemiology where infections compete to persist within a population.In studying models for such cases,one of the goals is to determine which infections can invade a population and persist when other infections are already resident within the population.Invasion reproductive numbers(IRN),which are tied to the stability of boundary endemic equilibria,can address this question.By reinterpreting resident infections epidemiologically,this study extends methods for finding IRNs to periodic systems,and presents some examples which illustrate the often complex computations required.Results identify conditions under which a simple time-average can be used to derive IRNs,and apply the methods to examine how seasonal fluctuations in influenza incidence facilitate the year-round persistence of bacterial respiratory infections.

Preliminary studies on occurrence of monensin antibiotic in Bosque River Watershed

Water quality impact due to excessive nutrients has been extensively studied. In recent years, however, micro-pollutants such as pharmaceuticals and hormonal products used in animal agriculture have added an additional impact to overall water quality. Pharmaceuticals used in the poultry, swine, beef, and dairy industries have been detected in various environmental matrices such as, soil, groundwater and surface water. In this study, 26 surface water samples were collected throughout the Bosque River Watershed （BRW） with samples representing a range of land use conditions and locations of major dairy operations. Samples were analyzed using commercially available Enzyme-Linked Immunosorbent Assay test. Of the 26 samples, three samples consistently tested positive for monensin antibiotic with concentration ranging from 0.30 to 3.41 μg/L. These three samples were collected from sites that received varying amount of agriculture wastes （11.7% to 31.3%） and located downstream from sites associated with moderate levels of animal agriculture. The preliminary results suggest that there is a potential for monensin occurrence in the BRW, although initial findings indicate only very low levels.