The metabolic impact of zinc oxide on porcine intestinal cells and enterotoxigenic Escherichia coli K88

Pharmacological levels of zinc oxide (ZnO) incorporated into the post-weaning piglet diet reduce the incidence of diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) K88. The mechanism for this is not understood. Here, Intestinal Porcine Epithelial Cells (IPEC) J2 were used as an in vitro model of the porcine intestine. ZnO reduced IPEC J2 viability at concentrations >= 200 mu M, and ETEC adhesion to the host cell was unaffected by ZnO. Characterisation of the metabolism of IPEC J2 cells and ETEC established the effects of ZnO treatment on the metabolic profile of both. Although 100 mu M ZnO did not inhibit growth of either host or pathogen in fully supplemented media, metabolic profiles were significantly altered. Glucose and mannose were essential energy sources for IPEC J2 cells in the presence of ZnO, as the ability to utilise other sources was compromised. The increase in specificity of requirements to support respiration in ETEC was more pronounced, in particular the need for cysteine as a nitrogen source. These findings indicate that ZnO impacts on both host cell and pathogen metabolism and may provide insight into the mechanism for diarrhoea reduction. (C) 2010 Elsevier B.V. All rights reserved.

SPI-23 of S.Derby: role in adherence and invasion of porcine tissues

Salmonella enterica serovars Derby and Mbandaka are isolated from different groups of livestock species in the UK. S. Derby is predominantly isolated from pigs and turkeys and S. Mbandaka is predominantly isolated from cattle and chickens. Alignment of the genome sequences of two isolates of each serovar led to the discovery of a new putative Salmonella pathogenicity island, SPI-23, in the chromosome sequence of S. Derby isolates. SPI-23 is 37 kb in length and contains 42 ORFs, ten of which are putative type III effector proteins. In this study we use porcine jejunum derived cell line IPEC-J2 and in vitro organ culture of porcine jejunum and colon, to characterise the association and invasion rates of S. Derby and S. Mbandaka, and tissue tropism of S. Derby respectively. We show that S. Derby invades and associates to an IPEC-J2 monolayer in significantly greater numbers than S. Mbandaka, and that S. Derby preferentially attaches to porcine jejunum over colon explants. We also show that nine genes across SPI-23 are up-regulated to a greater degree in the jejunum compared to the colon explants. Furthermore, we constructed a mutant of the highly up-regulated, pilV-like gene, potR, and find that it produces an excess of surface pili compared to the parent strain which form a strong agglutinating phenotype interfering with association and invasion of IPEC-J2 monolayers. We suggest that potR may play a role in tissue tropism.

Population structure and associated phenotypes of Salmonella enterica serovars Derby and Mbandaka overlap with host range

BACKGROUND:The Salmonella enterica serovar Derby is frequently isolated from pigs and turkeys whereas serovar Mbandaka is frequently isolated from cattle, chickens and animal feed in the UK. Through comparative genomics, phenomics and mutant construction we previously suggested possible mechanistic reasons why these serovars demonstrate apparently distinct host ranges. Here, we investigate the genetic and phenotypic diversity of these two serovars in the UK. We produce a phylogenetic reconstruction and perform several biochemical assays on isolates of S. Derby and S. Mbandaka acquired from sites across the UK between the years 2000 and 2010. RESULTS:We show that UK isolates of S. Mbandaka comprise of one clonal lineage which is adapted to proficient utilisation of metabolites found in soya beans under ambient conditions. We also show that this clonal lineage forms a biofilm at 25 °C, suggesting that this serovar maybe well adapted to survival ex vivo, growing in animal feed. Conversely, we show that S. Derby is made of two distinct lineages, L1 and L2. These lineages differ genotypically and phenotypically, being divided by the presence and absence of SPI-23 and the ability to more proficiently invade porcine jejunum derived cell line IPEC-J2. CONCLUSION:The results of this study lend support to the hypothesis that the differences in host ranges of S. Derby and S. Mbandaka are adaptations to pathogenesis, environmental persistence, as well as utilisation of metabolites abundant in their respective host environments.

Influence of temperature on the motility of Pseudomonas oryzihabitans and control of Globodera rostochiensis

The motility and efficacy of Pseudomonas oryzihabitans as a biocontrol agent against the potato cyst nematode Globodera rostochiensis were studied with respect to temperature. The influence of soil moisture on bacterial movement was also tested. In a closed container trial, P. oryzihabitans significantly reduced invasion of second stage juveniles (J2) of G. rostochiensis in potato roots, its effect being more marked at 25 and 21 degreesC than at 17 degreesC. P. oryzihabitans motility in vitro was optimal at 26 degreesC and inhibited at temperatures below 18 degreesC. In soil, both temperature and matric potential affected bacterial movement. At 16 degreesC its movement and survival were suppressed, but they were unaffected at 25 degreesC. At both temperatures the biocontrol agent moved faster in the wetter (- 0.03 MPa) than in the drier soil (- 0.1 MPa). These results suggest that temperature is a key factor in determining the potential of P. or.yzihabitans as a biocontrol agent. (C) 2003 Elsevier Science Ltd. All rights reserved.

Influence of temperature on the motility of Pseudomonas oryzihabitans and control of Globodera rostochiensis

The motility and efficacy of Pseudomonas oryzihabitans as a biocontrol agent against the potato cyst nematode Globodera rostochiensis were studied with respect to temperature. The influence of soil moisture on bacterial movement was also tested. In a closed container trial, P. oryzihabitans significantly reduced invasion of second stage juveniles (J2) of G. rostochiensis in potato roots, its effect being more marked at 25 and 21 degreesC than at 17 degreesC. P. oryzihabitans motility in vitro was optimal at 26 degreesC and inhibited at temperatures below 18 degreesC. In soil, both temperature and matric potential affected bacterial movement. At 16 degreesC its movement and survival were suppressed, but they were unaffected at 25 degreesC. At both temperatures the biocontrol agent moved faster in the wetter (- 0.03 MPa) than in the drier soil (- 0.1 MPa). These results suggest that temperature is a key factor in determining the potential of P. or.yzihabitans as a biocontrol agent. (C) 2003 Elsevier Science Ltd. All rights reserved.

Factors affecting biological control effectiveness of Pasteuria penetrans in Meloidogyne javanica and the bacterial development in the nematode body

The invasion and infectivity of Meloidogyne javanica juveniles (J2) encumbered with spore of Pasteuria Penetrans were influenced by the temperature and the time J2 were in the soil before exposure to roots. The percentage of infected females decreased as the time juveniles spent in soil increased. When spore encumbered J2 were maintained at 30 degrees C the decrease in infection was greater than that at 18 degrees C. The thermal time requirements and the base temperature for P. penetrans development were estimated. The rate of development followed an exponential curve between 21 and 36 degrees C and the base temperature for development was estimated by extrapolation to be 18.5 degrees C. The effect of integrating a nematode resistant tomato cultivar with the biocontrol agent P. penetrans also was investigated. The ability of the biocontrol agent to reduce numbers of root-knot nematodes was dependent on the densities of the nematode and P. penetrans spores in the soil.

Response of free eggs on infective juvenile root-knot nematode Meloidogyne javanica through neem (Azadirachta indica A. Juss) amended soil

Air-dried and 3 mm pore size sieved soil was amended with neem crude formulations (leaves and cake) @ 3% w/w and a refined product, aza @ 0.05 and 0.1 w/w. Three days after treatment, 500 eggs of M. javanica held in 2 ml water were added in each dish. In another experiment, soil was amended with neem crude formulations @ 10. 5, 2.5 and 1% w/w and refined formulation aza @ 0.025, 0.05, 0.1 and 0.5% w/w. Three days after amendment 1000 plus minus 21 freshly hatched J2 held in 3 ml water were added to the amended soil. Untreated soil was kept as control. Comparison of treatments means showed that all the neem formulations caused significant reduction of hatching. Neem crude formulations were more effective in reducing hatching as compared to commercial product aza. Among the crude formulations, neem leaves were most effective in reducing hatching. In other experiment all the doses of neem crude and refined formulations differed significantly with control in reducing the mobility of juveniles. It was observed that by increasing the dose of the formulations the mobility was reduced accordingly.

The isolation of a single spore isolate of Pasteuria penetrans and its pathogenicity on Meloidogyne javanica

We have obtained a single spore isolate of Pasteuria penetrans, derived by allowing a single spore to attach to a second-stage juvenile (J2) of the root-knot nematode Meloidogyne javanica. By analysing DNA sequences at three different loci we have obtained evidence that the isolate is, indeed, genetically pure. We compared the ability of the single spore isolate and the parent population from which it was selected to attach to and parasitise both the original population of M. javanica on which it was isolated and a single egg mass line derived from it. There was no difference in the attachment of spores of the single spore isolate to juveniles compared to the parental population, although there were higher numbers of both attaching to J2 of the single egg mass line compared to its parental population. Judging from the numbers of egg masses and Pasteuria-infected females, the single spore isolate was less pathogenic to the parental population of M. javanica than was the parental spore population.

Techniques for image analysis of movement of juveniles of root-knot nematodes encumbered with Pasteuria penetrans spores

Root-knot nematodes (Meloidogyne spp.) are the most significant plant-parasitic nematodes that damage many crops all over the world. The free-living second stage juvenile (J2) is the infective stage that enters plants. The J2s move in the soil water films to reach the root zone. The bacterium Pasteuria penetrans is an obligate parasite of root-knot nematodes, is cosmopolitan, frequently encountered in many climates and environmental conditions and is considered promising for the control of Meloidogyne spp. The infection potential of P. penetrans to nematodes is well studied but not the attachment effects on the movement of root-knot nematode juveniles, image analysis techniques were used to characterize movement of individual juveniles with or without P. penetrans spores attached to their cuticles. Methods include the study of nematode locomotion based on (a) the centroid body point, (b) shape analysis and (c) image stack analysis. All methods proved that individual J2s without P. penetrans spores attached have a sinusoidal forward movement compared with those encumbered with spores. From these separate analytical studies of encumbered and unencumbered nematodes, it was possible to demonstrate how the presence of P. penetrans spores on a nematode body disrupted the normal movement of the nematode.

A search for invariant relative satellite motion

This report presents the canonical Hamiltonian formulation of relative satellite motion. The unperturbed Hamiltonian model is shown to be equivalent to the well known Hill-Clohessy-Wilshire (HCW) linear formulation. The in°uence of perturbations of the nonlinear Gravitational potential and the oblateness of the Earth; J2 perturbations are also modelled within the Hamiltonian formulation. The modelling incorporates eccentricity of the reference orbit. The corresponding Hamiltonian vector ¯elds are computed and implemented in Simulink. A numerical method is presented aimed at locating periodic or quasi-periodic relative satellite motion. The numerical method outlined in this paper is applied to the Hamiltonian system. Although the orbits considered here are weakly unstable at best, in the case of eccentricity only, the method ¯nds exact periodic orbits. When other perturbations such as nonlinear gravitational terms are added, drift is signicantly reduced and in the case of the J2 perturbation with and without the nonlinear gravitational potential term, bounded quasi-periodic solutions are found. Advantages of using Newton's method to search for periodic or quasi-periodic relative satellite motion include simplicity of implementation, repeatability of solutions due to its non-random nature, and fast convergence. Given that the use of bounded or drifting trajectories as control references carries practical di±culties over long-term missions, Principal Component Analysis (PCA) is applied to the quasi-periodic or slowly drifting trajectories to help provide a closed reference trajectory for the implementation of closed loop control. In order to evaluate the e®ect of the quality of the model used to generate the periodic reference trajectory, a study involving closed loop control of a simulated master/follower formation was performed. 2 The results of the closed loop control study indicate that the quality of the model employed for generating the reference trajectory used for control purposes has an important in°uence on the resulting amount of fuel required to track the reference trajectory. The model used to generate LQR controller gains also has an e®ect on the e±ciency of the controller.

A new tetranuclear copper(II) complex with oximate bridges: structure, magnetic properties and DFT study

A new tetranuclear complex, [Cu4L4](ClO4)4·2H2O (1), has been synthesized from the self-assembly of copper(II) perchlorate and the tridentate Schiff base ligand (2E,3E)-3-(2-aminopropylimino) butan-2-one oxime (HL). Single-crystal X-ray diffraction studies reveal that complex 1 consists of a Cu4(NO)4 core where the four copper(II) centers having square pyramidal environment are arranged in a distorted tetrahedral geometry. They are linked together by a rare bridging mode (μ3-η1,η2,η1) of oximato ligands. Analysis of magnetic susceptibility data indicates moderate antiferromagnetic (J1 = −48 cm−1, J2 = −40 cm−1 and J3 = −52 cm−1) exchange interaction through σ-superexchange pathways (in-plane bridging) of the oxime group. Theoretical calculations based on DFT technique have been used to obtain the energy states of different spin configurations and estimate the coupling constants and to understand the exact magnetic exchange pathways.

Structure and magnetic properties of a tetranuclear Cu(II) complex containing the 2-(pyridine-2-yliminomethyl)-phenol ligand

A tetranuclear Cu(II) complex [Cu4L4(H2O)4](ClO4)4 has been synthesized using the terdentate Schiff base 2-(pyridine-2-yliminomethyl)-phenol (HL) (the condensation product of salicylaldehyde and 2-aminopyridine) and copper perchlorate. Chemical characterizations such as IR and UV/Vis of the complex have been carried out. A single-crystal diffraction study shows that the complex contains a nearly planar tetranuclear core containing four copper atoms, which occupy four equivalent five-coordinate sites with a square pyramidal environment. Magnetic measurements have been carried out over the temperature range 2–300K and with 100Oe field strengths. Analysis of magnetic susceptibility data indicates a strong antiferromagnetic (J1=−638cm−1) exchange interaction between diphenoxo-bridged Cu(II) centers and a moderate antiferromagnetic (J2=−34cm−1) interaction between N–C–N bridged Cu(II) centers. Magnetic exchange interactions (J’s) are also discussed on the basis of a computational study using DFT methodology. The spin density distribution (singlet ground state) is calculated to visualize the effect of delocalization of spin density through bridging groups.