17 research outputs found
Association of Polyphosphate (poly P) Kinases with Campylobacter jejuni Invasion and Survival in Human Epithelial Cells
No full textTransducer Like Proteins of Campylobacter jejuni 81-176: Role in chemotaxis and colonization of the chicken gastrointestinal tract
No full textTransducer Like Proteins (Tlps), also known as Methyl accepting chemotaxis proteins (MCP), enable enteric pathogens to respond to changing nutrient levels in the environment by mediating taxis towards or away from specific chemoeffector molecules such as nutrients. Despite recent advances in the characterization of chemotaxis responses in Campylobacter jejuni, the impact of Tlps on the adaptation of this pathogen to disparate niches and hosts is not fully characterized. The latter is particularly evident in the case of C. jejuni 81-176, a strain that is known to be highly invasive. Furthermore, the cytoplasmic group C Tlps (Tlp5, 6, and 8) was not extensively evaluated. Here, we investigated the role of C. jejuni 81-176 Tlps in chemotaxis towards various substrates, biofilm formation, in vitro interaction with human intestinal cells, and chicken colonization. We found that the ∆tlp6 and ∆tlp10 mutants exhibited decreased chemotaxis towards aspartate whereas the ∆tlp6 mutant displayed a decreased chemotaxis towards Tri-Carboxylic Acid (TCA) cycle intermediates such as pyruvate, isocitrate, and succinate. Our findings also corroborated that more than one Tlp is involved in mediating chemotaxis towards the same nutrient. The deletion of tlps affected important phenotypes such as motility, biofilm formation, and invasion of human intestinal epithelial cells (INT-407). The ∆tlp8 mutant displayed increased motility in soft agar and showed decreased biofilm formation. The ∆tlp8 and ∆tlp9 mutants were significantly defective in invasion in INT-407 cells. The ∆tlp10 mutant was defective in colonization of the chicken proximal and distal gastrointestinal tract, while the ∆tlp6 and ∆tlp8 mutants showed reduced colonization of the duodenum and jejunum. Our results highlight the importance of Tlps in C. jejuni’s adaptation and pathobiology
Discovery of novel small molecule modulators of Clavibacter michiganensis subsp. michiganensis
No full textClavibacter michiganensis subsp. michiganensis (Cmm) is a Gram-positive seed-transmitted bacterial phytopathogen responsible for substantial economic losses by adversely affecting tomato production worldwide. A high-throughput, cell-based screen was adapted to identify novel small molecule growth inhibitors to serve as leads for future bactericide development. A library of 4,182 compounds known to be bioactive against Saccharomyces cerevisiae was selected for primary screening against Cmm wild-type strain C290 for whole-cell growth inhibition. Four hundred sixty-eight molecules (11.2% hit rate) were identified as bacteriocidal or bacteriostatic against Cmm at 200 M. Seventy-seven candidates were selected based on Golden Triangle analyses for secondary screening. Secondary screens showed that several of these candidates were strain-selective. Several compounds were inhibitory to multiple Cmm strains as well as Bacillus subtilis, but not Pseudomonas fluorescens, Mitsuaria sp., Lysobacter enzymogenes, Lactobacillus rhamnosus, Bifidobacter animalis, or Escherichia coli. Most of the compounds were not phytotoxic and did not show overt host toxicity. Using a novel 96-well bioluminescent Cmm seedling infection assay, we assessed effects of selected compounds on pathogen infection. The 12 most potent novel molecules were identified by compiling the scores from all secondary screens combined with the reduction of pathogen infection in planta. When tested for ability to develop resistance to the top-12 compounds, no resistant Cmm were recovered, suggesting that the discovered compounds are unlikely to induce resistance. In conclusion, here we report top-12 compounds that provide chemical scaffolds for future Cmm-specific bactericide development
Okelo, an enslaved child, beyond literary fiction
No full textEn este artículo pretendo revelar la profunda base antropológica de la novela afroperuana Okelo, un niño esclavizado (Lima, 2021) de León Zamora, que da cuenta del complejo proceso sociocultural y psicológico del fenómeno de la esclavización en el Perú. Principalmente, destaco cómo el autor levanta una serie de cuestiones relevantes del fenómeno histórico de la esclavización africana en nuestro país que no han sido abordadas, de manera suficiente, desde una perspectiva antropológica y decolonizadora, tales como la visión tribal y colonialista de África, el impacto de la diversidad étnica de la población esclava en la construcción de una nueva identidad, la herencia cultural africana, los procesos de choque intercultural experimentados en América, el procesamiento del trauma de la esclavización, etc. Por último, hago una valoración positiva de la novela como un espacio de encuentro interdisciplinar para realizar una aproximación profunda, fundamentada y crítica de la esclavización africana en nuestro país.In this article I intend to reveal the deep anthropological basis of the Afro-Peruvian novel Okelo, an enslaved child (Lima, 2021) by León Zamora, which accounts for the complex sociocultural and psychological process of the phenomenon of enslavement in Peru. Mainly, I highlight how the author raises a series of relevant issues of the historical phenomenon of African enslavement in our country that have not been addressed sufficiently from an anthropological and decolonizing perspective; such as the tribal and colonialist visión of Africa, the impact of the ethnic diversity of the slave population on the construction of a new identity, the African cultural heritage, the processes of intercultural clash experienced in America, the processing of the trauma of enslavement, etc. Finally, make a positive assessment of the novel as an interdisciplinary meeting space to carry out a deep, well-founded and critical approach to African enslavement in our country
Infection with anthroponotic Cryptosporidium parvum does not fully protect the host against a subsequent challenge with C . hominis
No full textNovel anti-campylobacter compounds identified using high throughput screening of a pre-selected enriched small molecules library
No full textCampylobacter is a leading cause of foodborne bacterial gastroenteritis worldwide and infections can be fatal. The emergence of antibiotic-resistant Campylobacter spp. necessitates the development of new antimicrobials. We identified novel anti-Campylobacter small molecule inhibitors using a high throughput growth inhibition assay. To expedite screening, we made use of a "bioactive" library of 4182 compounds that we have previously shown to be active against diverse microbes. Screening for growth inhibition of Campylobacter jejuni, identified 781 compounds that were either bactericidal or bacteriostatic at a concentration of 200 μM. Seventy nine of the bactericidal compounds were prioritized for secondary screening based on their physico-chemical properties. Based on the minimum inhibitory concentration against a diverse range of C. jejuni and a lack of effect on gut microbes, we selected 12 compounds. No resistance was observed to any of these 12 lead compounds when C. jejuni was cultured with lethal or sub-lethal concentrations suggesting that C. jejuni is less likely to develop resistance to these compounds. Top 12 compounds also possessed low cytotoxicity to human intestinal epithelial cells (Caco-2 cells) and no hemolytic activity against sheep red blood cells. Next, these 12 compounds were evaluated for ability to clear C. jejuni in vitro. A total of 10 compounds had an anti-C. jejuni effect in Caco-2 cells with some effective even at 25 μM concentrations. These novel 12 compounds belong to five established antimicrobial chemical classes; piperazines, aryl amines, piperidines, sulfonamide, and pyridazinone. Exploitation of analogs of these chemical classes may provide Campylobacter specific drugs that can be applied in both human and animal medicine
Ischnopterapion (Ischnopterapion)
No full text<i>Ischnopterapion</i> (<i>Ischnopterapion</i>) sp. <p>(Fig. 14)</p> <p> A species found abundantly in the Pinar de Chio region of Tenerife in June 1999 was thought to be <i>I. plumbeomicans</i>. However, M. A. Alonso-Zarazaga (in litt.) has pointed out that this identification is unlikely, as that species is monophagous on <i>Lotus creticus</i>. The weevils were shaken from moribund plants of a species of <i>Lotus</i> identified as <i>L. campylocladus</i>, and occurred with smaller numbers of <i>Tychius colonnellii</i> Caldara, 1991 (= <i>T. filirostris</i> Wollaston, 1854) (Curculionidae). W. Suppantschitsch (in litt.) has also taken this species and suggested that, as specimens differ somewhat from typical <i>I. plumbeomicans</i>, it may represent an undescribed species; further study is indicated. The same species also occurred in abundance on <i>Lotus spartioides</i> at Cortijo de la Tirma, Gran Canaria, in January 2004 and less abundantly at on <i>Lotus</i> sp. at Epina, La Gomera, 27–29 April 2008 (current author’s records).</p>Published as part of <i>Morris, Michael G., Sw, London & Dt, Dorset, 2011, The Apionidae (Coleoptera) of the Canary Islands, with particular reference to the contribution of T. Vernon Wollaston, pp. 157-182 in Acta Entomologica Musei Nationalis Pragae 51 (1)</i> on page 179, DOI: <a href="http://zenodo.org/record/5327310">10.5281/zenodo.5327310</a>
New and renewable energy and environmental engineering
No full textThere is an acute scarcity of potable water in many parts of the world, and especially in most of the Middle East region. Important advances have been made in desalination technology but its wide application is restricted by relatively high capital and input energy costs, even when solar energy is used. Until recently, flat-plate solar collectors have usually been employed to distill water in compact desalination systems. Currently, it is possible to replace these collectors by the more advanced evacuated tube collectors, which are now available on the market at a similar price. The research which is concerned with the development of a novel small scale solar water desalination technology, consists of experimental and theoretical investigations of the operation of a multi stage solar still desalination system coupled with a heat pipe evacuated tube solar collector with an aperture area of about 1.7 m(^2). The multi stage still was tested to recover latent heat from the evaporation and condensation processes in each of its four stages. A number of experimental tests were carried out using a laboratory rig to investigate its water production capacity. Solar radiation (insolation) during a mid-summer day in the Middle East region was simulated by an array of 110 halogen flood lights. Computational Fluid Dynamics (CFD) modeling of the evaporation and condensation processes in one of the still's stages was conducted using FLUENT 6.2 software. The simulation results demonstrate the importance of the various parameters affecting the total production rate of the solar still and provide detailed information on the temperature distribution and condensate formation inside the solar still. However, it was found that the CFD technique at this stage does not provide accurate quantitative predictions and results obtained can be used only for qualitative analysis. Hence, the use of a lumped parameter mathematical model was preferred for analysis and design purpose. A lumped parameter model has been developed to describe the system's operation. It consists of a system of ordinary differential equations of energy and mass conservation written for each stage of the still. A MATLAB computer program was written to solve the system of governing equations to simulate the evaporation and condensation processes and the experimental results were used to validate numerical predictions. The experimental and theoretical values for the total daily distillate output were found to be closely correlated. The test results demonstrate that the system produces about 9 kg of clean water per day and has a distillation efficiency of 90%. The overall efficiency is 33% due to the presence of heat losses in the system. However, this level of efficiency is greater of that for conventional solar stills. Following the experimental calibration of the lumped parameter model, this was used for determination of rational design parameters of the still and it was demonstrated that the performance of the system could be considerably improved to produce 11 kg/m(^2) of water per day if the number of stages and evaporation area were 4 and 1 m(^2), respectively. A water quality analysis was performed for the distilled water and the levels of total dissolved solids, electrical conductivity and pH were well within the range defined by the World Health Organization guidelines for drinking water. An economic study was also conducted for the system and it was shown that the distilled water costs of 0.016 US$/litre with a payback period of 6 months in the Middle East region conditions. This research demonstrates, empirically and theoretically, the potential role in the field of solar desalination of the multistage solar still coupled to the evacuated tube solar collector. Not only is this system a promising new technology but it could prove to be particularly appropriate in remote and rural areas. Simultaneously this system also uses a completely clean energy source and contributes to tackling environmental pollution, global carbon emissions and climate change problems
Daily Cryptosporidium parvum oocyst excretion pattern following infection of the piglets of control sow #2 with C. parvum, and serum antibody titers on day of the infection (first bleed) and at euthanasia (second bleed).
No full text(XLSX)</p
Daily oocyst excretion pattern following infection of the piglets with <i>Cryptosporidium parvum</i>.
No full textA) piglets of the control sow #2, and (B) immunized sow #4. (C) total oocyst excretion of each piglet of control and immunized sows over 17 days post-infection **p <0.0005.</p
