Mini-review on the efficacy of aquatic macrophytes as mosquito larvicide

Malaria is a mosquito-borne disease, which is endemic in Asia, Africa and Latin America. Vector control is the current strategy used for the eradication and elimination of malaria in these countries, but this control method has not proven to be effective, as malaria continues its increasing trend. Although chemical larvicide can also be used to eradicate the malaria vector at the larval stage, preventing the growth of mosquitoes into hematophagous adults, the continuous use of chemical insecticides leads to environmental pollution. It is therefore of paramount importance to identify effective, low-cost, biodegradable and environmentally friendly alternatives to chemical insecticides for the control of mosquito larvae.This mini-review aims to assess the present and future of the use of macrophytes as a mosquito larvicide. We critically analyze the trend of malaria cases in sub-Saharan Africa and evaluate why botanical larvicides may contribute to the eradication of malaria in the region. The ecological role of macrophytes in the aquatic environment and their potential as botanical larvicide are explained in detail. The study illustrates that the macrophytes Azolla pinnata, Pistia stratiotes, Eicchornia crassipes, Phragmites australis, Nelumbo nucifera, Nymphaea lotus, Typha latifolia and Leucas martinicensis have been effectively used as larvicides against mosquito larvae. It is recommended that additional work be done to purify the biologically active components that are responsible for the larvicidal activity of these macrophytes, and future research should assess the potential of other macrophytes for effective utilization as larvicides

Topological data analysis of Escherichia coli O157:H7 and non-O157 survival in soils.

Shiga toxin-producing E. coli O157:H7 and non-O157 have been implicated in many foodborne illnesses caused by the consumption of contaminated fresh produce. However, data on their persistence in soils are limited due to the complexity in datasets generated from different environmental variables and bacterial taxa. There is a continuing need to distinguish the various environmental variables and different bacterial groups to understand the relationships among these factors and the pathogen survival. Using an approach called Topological Data Analysis (TDA); we reconstructed the relationship structure of E. coli O157 and non-O157 survival in 32 soils (16 organic and 16 conventionally managed soils) from California (CA) and Arizona (AZ) with a multi-resolution output. In our study, we took a community approach based on total soil microbiome to study community level survival and examining the network of the community as a whole and the relationship between its topology and biological processes. TDA produces a geometric representation of complex data sets. Network analysis showed that Shiga toxin negative strain E. coli O157:H7 4554 survived significantly longer in comparison to E. coli O157:H7 EDL 933, while the survival time of E. coli O157:NM was comparable to that of E. coli O157:H7 EDL 933 in all of the tested soils. Two non-O157 strains, E. coli O26:H11 and E. coli O103:H2 survived much longer than E. coli O91:H21 and the three strains of E. coli O157. We show that there are complex interactions between E. coli strain survival, microbial community structures, and soil parameters

Persistence of Escherichia coli O157:H7 and Its Mutants in Soils

The persistence of Shiga toxin-producing E. coli O157:H7 in the environment poses a serious threat to public health. However, the role of Shiga toxins and other virulence factors in the survival of E. coli O157:H7 is poorly defined. The aim of this study was to determine if the virulence factors, stx1, stx2, stx1–2, and eae in E. coli O157:H7 EDL933 play any significant role in the growth of this pathogen in rich media and in soils. Isogenic deletion mutants that were missing one of four virulence factors, stx1, stx2, stx1–2, and eae in E. coli O157:H7 EDL933 were constructed, and their growth in rich media and survival in soils with distinct texture and chemistry were characterized. The survival data were successfully analyzed using Double Weibull model, and the modeling parameters of the mutant strains were not significantly different from those of the wild type. The calculated Td (time needed to reach the detection limit, 100 CFU/g soil) for loamy sand, sandy loam, and silty clay was 32, 80, and 110 days, respectively. It was also found that Td was positively correlated with soil structure (e.g. clay content), and soil chemistry (e.g. total nitrogen, total carbon, and water extractable organic carbon). The results of this study showed that the possession of Shiga toxins and intimin in E. coli O157:H7 might not play any important role in its survival in soils. The double deletion mutant of E. coli O157:H7 (stx1−stx2−) may be a good substitute to use for the investigation of transport, fate, and survival of E. coli O157:H7 in the environment where the use of pathogenic strains are prohibited by law since the mutants showed the same characteristics in both culture media and environmental samples

Secondary development based on 3D Slicer extension modules

Slicer module is an important part of software, which provides algorithmic support for data processing for the realization of various functions of software. As an external plug-in that needs to be installed, extensions have strong independence. Developers can redevelop the original extension module and modify its functions and interfaces in order to achieve better results to meet the requirements of medical use. In this paper, the feasibility scheme and specific operation steps for the secondary development of the extended module are proposed, so as to improve efficiency, simplify the operation process, and facilitate the use of Slicer software in clinical medicine and medical research

Assimilable Organic Carbon (AOC) in Soil Water Extracts Using Vibrio harveyi BB721 and Its Implication for Microbial Biomass

Assimilable organic carbon (AOC) is commonly used to measure the growth potential of microorganisms in water, but has not yet been investigated for measuring microbial growth potential in soils. In this study, a simple, rapid, and non-growth based assay to determine AOC in soil was developed using a naturally occurring luminous strain Vibrio harveyi BB721 to determine the fraction of low molecular weight organic carbon in soil water extract. Calibration of the assay was achieved by measuring the luminescence intensity of starved V. harveyi BB721 cells in the late exponential phase with a concentration range from 0 to 800 µg l−1 glucose (equivalent to 0–16.0 mg glucose C kg−1 soil) with the detection limit of 10 µg l−1 equivalent to 0.20 mg glucose C kg−1 soil. Results showed that bioluminescence was proportional to the concentration of glucose added to soil. The luminescence intensity of the cells was highly pH dependent and the optimal pH was about 7.0. The average AOC concentration in 32 soils tested was 2.9±2.2 mg glucose C kg−1. Our data showed that AOC levels in soil water extracts were significantly correlated (P<0.05) with microbial biomass determined as microbial biomass carbon, indicating that the AOC concentrations determined by the method developed might be a good indicator of soil microbial biomass. Our findings provide a new approach that may be used to determine AOC in environmental samples using a non-growth bioluminescence based assay. Understanding the levels of AOC in soil water extract provides new insights into our ability to estimate the most available carbon pool to bacteria in soil that may be easily assimilated into cells for many metabolic processes and suggest possible the links between AOC, microbial regrowth potential, and microbial biomass in soils

Light-assisted decomposition of dyes over iron-bearing soil clays in the presence of H2O2

Four types of soil clays from different sites in China have been chosen to simulate chemical remediation of soils contaminated with dyes by light-assisted Fenton-like method. X-Ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS) and electron spin resonance (ESR) measurements indicated that these soil clays contain iron oxides such as magnetite and hematite, where nondistorted iron active sites (ESR spectra, g = 2.3) predominate. Upon visible or UV irradiation, the soil clays were very effective for the degradation of nonbiodegradable cationic dyes such as Rhodamine B (RhB) by activating H2O2 at neutral pH. The photodegradation rates of RhB were closely related to total Fe content in clays and H2O2 dosage, indicating the mineral-catalyzed Fenton-like reactions operated. Soil organic matters (SOM) would remarkably inhibit the photodecomposition of RhB dye. The reaction products were some low-molecular-weight dicarboxylic acids and their derivatives, all of which are easily biodegradable. A possible mechanism was proposed based on the results obtained by spin-trapping ESR technique

Persistence of Salmonella Typhimurium in Well Waters from a Rural Area of Changchun City, China

Salmonella-contaminated well water could cause major infection outbreaks worldwide, thus, it is crucial to understand their persistence in those waters. In this study, we investigated the persistence of Salmonella enterica serovar Typhimurium in 15 well waters from a rural area of Changchun City, China. Results illustrated that the time to reach detection limit (ttd), first decimal reduction time (&delta;), and the shape parameter (p) ranged from 15 to 80 days, from 5.6 to 66.9 days, and from 0.6 to 6.6, respectively. Principal component analysis showed that ttds of S. Typhimurium were positively correlated with total organic carbon, pH, NH4+&ndash;N, and total phosphate. Multiple stepwise regression analysis revealed that ttds could be best predicted by NH4+&ndash;N and pH. Canonical correspondence analysis and variation partition analysis revealed that NH4+&ndash;N and pH, and the rest of the water parameters, could explain 27.60% and 28.15% of overall variation of the survival behavior, respectively. In addition, ttds were found to be correlated (p &lt; 0.01) with &delta; and p. Our results showed that the longer survival (&gt;2.5 months) S. Typhimurium could constitute an increased health risk to the local communities, and provided insights into the close linkage between well water quality and survival of S. Typhimurium