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1
COX, F. E. G. "Concomitant infections, parasites and immune responses". Parasitology 122, S1 (marzec 2001): S23—S38. http://dx.doi.org/10.1017/s003118200001698x.
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Concomitant infections are common in nature and often involve parasites. A number of examples of the interactions between protozoa and viruses, protozoa and bacteria, protozoa and other protozoa, protozoa and helminths, helminths and viruses, helminths and bacteria, and helminths and other helminths are described. In mixed infections the burden of one or both the infectious agents may be increased, one or both may be suppressed or one may be increased and the other suppressed. It is now possible to explain many of these interactions in terms of the effects parasites have on the immune system, particularly parasite-induced immunodepression, and the effects of cytokines controlling polarization to the Th1or Th2arms of the immune response. In addition, parasites may be affected, directly or indirectly, by cytokines and other immune effector molecules and parasites may themselves produce factors that affect the cells of the immune system. Parasites are, therefore, affected when they themselves, or other organisms, interact with the immune response and, in particular, the cytokine network. The importance of such interactions is discussed in relation to clinical disease and the development and use of vaccines.
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Gomes, Marta T., Angela H. Lopes i José Roberto Meyer-Fernandes. "Possible Roles of Ectophosphatases in Host-Parasite Interactions". Journal of Parasitology Research 2011 (2011): 1–7. http://dx.doi.org/10.1155/2011/479146.
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The interaction and survival of pathogens in hostile environments and in confrontation with host immune responses are important mechanisms for the establishment of infection. Ectophosphatases are enzymes localized at the plasma membrane of cells, and their active sites face the external medium rather than the cytoplasm. Once activated, these enzymes are able to hydrolyze phosphorylated substrates in the extracellular milieu. Several studies demonstrated the presence of surface-located ecto-phosphatases in a vast number of pathogenic organisms, including bacteria, protozoa, and fungi. Little is known about the role of ecto-phosphatases in host-pathogen interactions. The present paper provides an overview of recent findings related to the virulence induced by these surface molecules in protozoa and fungi.
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INGHAM, E. R., C. CAMBARDELLA i D. C. COLEMAN. "MANIPULATION OF BACTERIA, FUNGI AND PROTOZOA BY BIOCIDES IN LODGEPOLE PINE FOREST SOIL MICROCOSMS: EFFECTS ON ORGANISM INTERACTIONS AND NITROGEN MINERALIZATION". Canadian Journal of Soil Science 66, nr 2 (1.05.1986): 261–72. http://dx.doi.org/10.4141/cjss86-028.
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Biocides were applied singly and in combination to determine their effect on target and nontarget microorganisms in mineral soil from a lodgepole pine forest and to determine microbial interaction effects on N mineralization. Soil was sterilized and reinoculated with field populations of bacteria, fungi and protozoa. Streptomycin (a bactericide), fungizone (a saprophytic fungicide), chloroform (reduces protozoa and a portion of the bacteria and fungi), a combination of cygon (an acaricide), carbofuran (an insecticide-nematicide) and chloroform and a combination of streptomycin and fungizone were used. Reduction of bacteria produced the same decreases in N immobilization and increases in soil inorganic N in forest soil as observed previously in grassland soil. Further, reduction of fungi decreased N mineralization. Chloroform reduced protozoa to below detection limits, reduced bacterial populations 2- to 10-fold, but only reduced fungal populations by twofold. Despite reductions in both bacteria and fungi, NH+4-N increased similarly to streptomycin treatments where only bacteria were reduced. When fungal populations increased after a reduction in bacterial populations, inorganic N concentrations increased. However, when fungal populations were reduced, bacterial populations did not increase, suggesting that bacteria do not compete with fungi for substrates. Key words: Microbial ecology, N mineralization, streptomycin, amphotericin B, chloroform, pesticide effects, lodgepole pine soil
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Gourabathini, Poornima, Maria T. Brandl, Katherine S. Redding, John H. Gunderson i Sharon G. Berk. "Interactions between Food-Borne Pathogens and Protozoa Isolated from Lettuce and Spinach". Applied and Environmental Microbiology 74, nr 8 (29.02.2008): 2518–25. http://dx.doi.org/10.1128/aem.02709-07.
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ABSTRACT The survival of Salmonella enterica was recently shown to increase when the bacteria were sequestered in expelled food vacuoles (vesicles) of Tetrahymena. Because fresh produce is increasingly linked to outbreaks of enteric illness, the present investigation aimed to determine the prevalence of protozoa on spinach and lettuce and to examine their interactions with S. enterica, Escherichia coli O157:H7, and Listeria monocytogenes. Glaucoma sp., Colpoda steinii, and Acanthamoeba palestinensis were cultured from store-bought spinach and lettuce and used in our study. A strain of Tetrahymena pyriformis previously isolated from spinach and a soil-borne Tetrahymena sp. were also used. Washed protozoa were allowed to graze on green fluorescent protein- or red fluorescent protein-labeled enteric pathogens. Significant differences in interactions among the various protist-enteric pathogen combinations were observed. Vesicles were produced by Glaucoma with all of the bacterial strains, although L. monocytogenes resulted in the smallest number per ciliate. Vesicle production was observed also during grazing of Tetrahymena on E. coli O157:H7 and S. enterica but not during grazing on L. monocytogenes, in vitro and on leaves. All vesicles contained intact fluorescing bacteria. In contrast, C. steinii and the amoeba did not produce vesicles from any of the enteric pathogens, nor were pathogens trapped within their cysts. Studies of the fate of E. coli O157:H7 in expelled vesicles revealed that by 4 h after addition of spinach extract, the bacteria multiplied and escaped the vesicles. The presence of protozoa on leafy vegetables and their sequestration of enteric bacteria in vesicles indicate that they may play an important role in the ecology of human pathogens on produce.
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Clarholm, Marianne. "Interactions of bacteria, protozoa and plants leading to mineralization of soil nitrogen". Soil Biology and Biochemistry 17, nr 2 (styczeń 1985): 181–87. http://dx.doi.org/10.1016/0038-0717(85)90113-0.
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Yan, Ling, Ronald L. Cerny i Jeffrey D. Cirillo. "Evidence that hsp90 Is Involved in the Altered Interactions of Acanthamoeba castellanii Variants with Bacteria". Eukaryotic Cell 3, nr 3 (czerwiec 2004): 567–78. http://dx.doi.org/10.1128/ec.3.3.567-578.2004.
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ABSTRACT There are many similarities between the interactions of environmental protozoa with pathogenic bacterial species and those observed in mammalian macrophages. Since single-celled protozoa predate mammalian hosts, it is likely that interactions in environmental biofilms have selected for many of the bacterial virulence mechanisms responsible for human disease. In order to better understand bacterial-phagocyte interactions, we developed a selection for Acanthamoeba castellanii variants that are more resistant to killing by bacterial pathogens. We identified four amoebal clones that display decreased phagocytosis of bacteria but no difference in uptake of latex beads compared to wild-type amoebae. These amoebal variants display differences in cellular morphology, partial resistance to killing by bacteria, more bactericidal activity, and higher frequencies of lysosome fusion with the bacterial vacuole. Three proteins are present at lower levels in these variants than in wild-type amoebae, and matrix-assisted laser desorption ionization-time of flight mass spectrometry allowed identification of two of them as actin and hsp90. We found that specific inhibitors of hsp90 produce a similar phenotypic effect in macrophages. These data suggest that hsp90 plays a role in phagocytic and, possibly, bactericidal pathways that affect interactions of phagocytic cells with bacteria.
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Pinto, Ameet J., i Nancy G. Love. "Bioreactor Function under Perturbation Scenarios Is Affected by Interactions between Bacteria and Protozoa". Environmental Science & Technology 46, nr 14 (6.07.2012): 7558–66. http://dx.doi.org/10.1021/es301220f.
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Newbold, C. J., P. W. Griffin i R. J. Wallace. "Interactions between rumen bacteria and ciliate protozoa in their attachment to barley straw". Letters in Applied Microbiology 8, nr 2 (luty 1989): 63–66. http://dx.doi.org/10.1111/j.1472-765x.1989.tb00224.x.
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Yu, Jiangkun, Liyuan Cai, Jiacai Zhang, Ao Yang, Yanan Wang, Lei Zhang, Le Luo Guan i Desheng Qi. "Effects of Thymol Supplementation on Goat Rumen Fermentation and Rumen Microbiota In Vitro". Microorganisms 8, nr 8 (30.07.2020): 1160. http://dx.doi.org/10.3390/microorganisms8081160.
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This study was performed to explore the predominant responses of rumen microbiota with thymol supplementation as well as effective dose of thymol on rumen fermentation. Thymol at different concentrations, i.e., 0, 100 mg/L, 200 mg/L, and 400 mg/L (four groups × five replications) was applied for 24 h of fermentation in a rumen fluid incubation system. Illumina MiSeq sequencing was applied to investigate the ruminal microbes in addition to the examination of rumen fermentation. Thymol doses reached 200 mg/L and significantly decreased (p < 0.05) total gas production (TGP) and methane production; the production of total volatile fatty acids (VFA), propionate, and ammonia nitrogen, and the digestibility of dry matter and organic matter were apparently decreased (p < 0.05) when the thymol dose reached 400 mg/L. A thymol dose of 200 mg/L significantly affected (p < 0.05) the relative abundance of 14 genera of bacteria, three species of archaea, and two genera of protozoa. Network analysis showed that bacteria, archaea, and protozoa significantly correlated with methane production and VFA production. This study indicates an optimal dose of thymol at 200 mg/L to facilitate rumen fermentation, the critical roles of bacteria in rumen fermentation, and their interactions with the archaea and protozoa.
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Montelongo-Jauregui, Daniel, i Jose Lopez-Ribot. "Candida Interactions with the Oral Bacterial Microbiota". Journal of Fungi 4, nr 4 (3.11.2018): 122. http://dx.doi.org/10.3390/jof4040122.
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The human oral cavity is normally colonized by a wide range of microorganisms, including bacteria, fungi, Archaea, viruses, and protozoa. Within the different oral microenvironments these organisms are often found as part of highly organized microbial communities termed biofilms, which display consortial behavior. Formation and maintenance of these biofilms are highly dependent on the direct interactions between the different members of the microbiota, as well as on the released factors that influence the surrounding microbial populations. These complex biofilm dynamics influence oral health and disease. In the latest years there has been an increased recognition of the important role that interkingdom interactions, in particular those between fungi and bacteria, play within the oral cavity. Candida spp., and in particular C. albicans, are among the most important fungi colonizing the oral cavity of humans and have been found to participate in these complex microbial oral biofilms. C. albicans has been reported to interact with individual members of the oral bacterial microbiota, leading to either synergistic or antagonistic relationships. In this review we describe some of the better characterized interactions between Candida spp. and oral bacteria.
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Monteil, Caroline L., Nicolas Menguy, Sandra Prévéral, Alan Warren, David Pignol i Christopher T. Lefèvre. "Accumulation and Dissolution of Magnetite Crystals in a Magnetically Responsive Ciliate". Applied and Environmental Microbiology 84, nr 8 (9.02.2018): e02865-17. http://dx.doi.org/10.1128/aem.02865-17.
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ABSTRACTMagnetotactic bacteria (MTB) represent a group of microorganisms that are widespread in aquatic habitats and thrive at oxic-anoxic interfaces. They are able to scavenge high concentrations of iron thanks to the biomineralization of magnetic crystals in their unique organelles, the so-called magnetosome chains. Although their biodiversity has been intensively studied, their ecology and impact on iron cycling remain largely unexplored. Predation by protozoa was suggested as one of the ecological processes that could be involved in the release of iron back into the ecosystem. Magnetic protozoa were previously observed in aquatic environments, but their diversity and the fate of particulate iron during grazing are poorly documented. In this study, we report the morphological and molecular characterizations of a magnetically responsive MTB-grazing protozoan able to ingest high quantities of MTB. This protozoan is tentatively identified asUronema marinum, a ciliate known to be a predator of bacteria. Using light and electron microscopy, we investigated in detail the vacuoles in which the lysis of phagocytized prokaryotes occurs. We carried out high-resolution observations of aligned magnetosome chains and ongoing dissolution of crystals. Particulate iron in the ciliate represented approximately 0.01% of its total volume. We show the ubiquity of this interaction in other types of environments and describe different grazing strategies. These data contribute to the mounting evidence that the interactions between MTB and protozoa might play a significant role in iron turnover in microaerophilic habitats.IMPORTANCEIdentifying participants of each biogeochemical cycle is a prerequisite to our understanding of ecosystem functioning. Magnetotactic bacteria (MTB) participate in iron cycling by concentrating large amounts of biomineralized iron minerals in their cells, which impacts their chemical environment at, or below, the oxic-anoxic transition zone in aquatic habitats. It was shown that some protozoa inhabiting this niche could become magnetic by the ingestion of magnetic crystals biomineralized by grazed MTB. In this study, we show that magnetic MTB grazers are commonly observed in marine and freshwater sediments and can sometimes accumulate very large amounts of particulate iron. We describe here different phagocytosis strategies, determined using magnetic particles from MTB as tracers after their ingestion by the protozoa. This study paves the way for potential scientific or medical applications using MTB grazers as magnetosome hyperaccumulators.
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Rutherford, P. M., i N. G. Juma. "Performance of a simulation model describing protozoa-induced mineralization of bacterial C and N in a sandy loam". Canadian Journal of Soil Science 72, nr 3 (1.08.1992): 217–28. http://dx.doi.org/10.4141/cjss92-021.
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Mathematical modelling of a microcosm experiment provided a rigorous link between soil organism populations and the processes in the C and N cycles for a clay loam soil. In order to check the internal consistency of the model, we tested its performance with the data set obtained for a sandy loam. We empirically lowered the value of the half saturation constant for the protozoan consumption of bacteria from 175 to 50 (μg C g−1 soil) and initialized the state variables with the appropriate values. The model was also used to quantify the effect of texture on bacterial-protozoan interactions and flows of C and N using the simulated data for a clay loam and a sandy loam. The CO2-C evolved during the first 12 d was mainly due to glucose addition (180 μg C g−1 soil) and cycling of C in the soil (130 μg C g−1 soil). During this interval, C inputs into bacteria were 14-fold greater than the initial pool size. Protozoa increased total CO2-C evolution by 16% and increased net NH4-N mineralization 3.5-fold compared with the protozoa-minus treatment. Mineralization of bacterial C and N was more rapid in the sandy loam than in the clay loam. Key words: N mineralization-immobilization, bacteria, model, protozoa, Typic Cryoboroll, sandy loam
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Rabee, Alaa Emara, Robert Forster, Chijioke Elekwachi, Ebrahim Sabra i Mebarek Lamara. "Comparative analysis of the metabolically active microbial communities in the rumen of dromedary camels under different feeding systems using total rRNA sequencing". PeerJ 8 (29.10.2020): e10184. http://dx.doi.org/10.7717/peerj.10184.
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Breakdown of plant biomass in rumen depends on interactions between bacteria, archaea, fungi, and protozoa; however, the majority of studies of the microbiome of ruminants, including the few studies of the rumen of camels, only studied one of these microbial groups. In this study, we applied total rRNA sequencing to identify active microbial communities in 22 solid and liquid rumen samples from 11 camels. These camels were reared at three stations that use different feeding systems: clover, hay and wheat straw (G1), fresh clover (G2), and wheat straw (G3). Bacteria dominated the libraries of sequence reads generated from all rumen samples, followed by protozoa, archaea, and fungi respectively. Firmicutes, Thermoplasmatales, Diplodinium, and Neocallimastix dominated bacterial, archaeal, protozoal and fungal communities, respectively in all samples. Libraries generated from camels reared at facility G2, where they were fed fresh clover, showed the highest alpha diversity. Principal co-ordinate analysis and linear discriminate analysis showed clusters associated with facility/feed and the relative abundance of microbes varied between liquid and solid fractions. This provides preliminary evidence that bacteria dominate the microbial communities of the camel rumen and these communities differ significantly between populations of domesticated camels.
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Álvarez, Belén, María M. López i Elena G. Biosca. "Influence of Native Microbiota on Survival of Ralstonia solanacearum Phylotype II in River Water Microcosms". Applied and Environmental Microbiology 73, nr 22 (14.09.2007): 7210–17. http://dx.doi.org/10.1128/aem.00960-07.
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ABSTRACT Ralstonia solanacearum phylotype II biovar 2 causes bacterial wilt in solanaceous hosts, producing severe economic losses worldwide. Waterways can be major dissemination routes of this pathogen, which is able to survive for long periods in sterilized water. However, little is known about its survival in natural water when other microorganisms, such as bacteriophages, other bacteria, and protozoa, are present. This study looks into the fate of a Spanish strain of R. solanacearum inoculated in water microcosms from a Spanish river, containing different microbiota fractions, at 24°C and 14°C, for a month. At both temperatures, R. solanacearum densities remained constant at the initial levels in control microcosms of sterile river water while, by contrast, declines in the populations of the introduced strain were observed in the nonsterile microcosms. These decreases were less marked at 14°C. Lytic bacteriophages present in this river water were involved in the declines of the pathogen populations, but indigenous protozoa and bacteria also contributed to the reduced persistence in water. R. solanacearum variants displaying resistance to phage infection were observed, but only in microcosms without protozoa and native bacteria. In water microcosms, the temperature of 14°C was more favorable for the survival of this pathogen than 24°C, since biotic interactions were slower at the lower temperature. Similar trends were observed in microcosms inoculated with a Dutch strain. This is the first study demonstrating the influence of different fractions of water microorganisms on the survival of R. solanacearum phylotype II released into river water microcosms.
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Liddell, Keith, Vladimir Krivtsov, Harry Staines, Ann Brendler, Adam Garside i Bryan Griffiths. "A study of population numbers and ecological interactions of soil and forest floor microfauna". Animal Biology 57, nr 4 (2007): 467–84. http://dx.doi.org/10.1163/157075607782232189.
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AbstractMicroinvertebrate abundance was measured, together with forest soil properties and litter components in eight plots dominated by beech and birch during May to August 2001. The results were analysed using ANOVA, stepwise regression and correlation analysis. Both protozoa and nematodes were analysed according to their functional groups. The protozoa were flagellates, ciliates and naked amoebae, and the nematodes were microbial and plant feeding nematodes. Moisture levels were between 28% and 33% in soil, and 50% to 70% in litter. Population numbers were very variable between sites and dates, and showed variable levels between May and July followed by a significant increase in August.ANOVA showed significant site and date effects, mainly in the litter. Stepwise regression models and correlation analysis revealed a number of interactions among separate groups of protozoa and nematodes, as well as their interrelations with fungi and bacteria. In addition, statistical analysis of soil data revealed a number of microfaunal relationships with soil pH, moisture and organic content, whilst in the field layer a number of significant interactions with specific forest litter fractions were found.The results have revealed particularly high levels of microfaunal abundance in the litter fraction compared to the soil, with flagellates and microbial feeding nematodes showing the highest levels among the trophic groups studied. These data compare well with other studies in similar ecosystems. The invertebrates present appear to be concentrated in hotspots of biological activity. In soil, they may predominantly have been confined to the rhizosphere. In the litter, their numbers may have been enhanced by nutrient availability, which may have increased throughout the study period owing to the gradual progress of decomposition facilitated by the combination of faunal, bacterial and fungal activity.
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Torcato, Inês M., Miguel A. R. B. Castanho i Sónia T. Henriques. "The Application of Biophysical Techniques to Study Antimicrobial Peptides". Spectroscopy: An International Journal 27 (2012): 541–49. http://dx.doi.org/10.1155/2012/460702.
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The increasing bacteria resistance to conventional antibiotics has led to the need for alternative therapies. Being part of the human innate defence system and with a broad spectrum of activity against bacteria, viruses, protozoa, and cancer cells, antimicrobial peptides (AMPs) are a very promising alternative. The mechanism of action of AMPs seems to broadly correlate with their ability to target the bacterial cell membrane. To understand and improve their effect, it is of major importance to unravel their mechanism of action and, in particular, to understand the peptide-membrane binding. Several biophysical techniques such as fluorescence spectroscopy, circular dichroism, zeta potential determination, and atomic force microscopy can be used to achieve this goal. Characteristics of AMPs-membranes interactions and the use of these biophysical techniques will be discussed.
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Escalante, Nichole K., Paul Lemire, Mayra Cruz Tleugabulova, David Prescott, Arthur Mortha, Catherine J. Streutker, Stephen E. Girardin, Dana J. Philpott i Thierry Mallevaey. "The common mouse protozoa Tritrichomonas muris alters mucosal T cell homeostasis and colitis susceptibility". Journal of Experimental Medicine 213, nr 13 (11.11.2016): 2841–50. http://dx.doi.org/10.1084/jem.20161776.
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The mammalian gastrointestinal tract hosts a diverse community of microbes including bacteria, fungi, protozoa, helminths, and viruses. Through coevolution, mammals and these microbes have developed a symbiosis that is sustained through the host’s continuous sensing of microbial factors and the generation of a tolerant or pro-inflammatory response. While analyzing T cell–driven colitis in nonlittermate mouse strains, we serendipitously identified that a nongenetic transmissible factor dramatically increased disease susceptibility. We identified the protozoan Tritrichomonas muris as the disease-exacerbating element. Furthermore, experimental colonization with T. muris induced an elevated Th1 response in the cecum of naive wild-type mice and accelerated colitis in Rag1−/− mice after T cell transfer. Overall, we describe a novel cross-kingdom interaction within the murine gut that alters immune cell homeostasis and disease susceptibility. This example of unpredicted microbial priming of the immune response highlights the importance of studying trans-kingdom interactions and serves as a stark reminder of the importance of using littermate controls in all mouse research.
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Lee, S. S., J. K. Ha i K. J. Cheng. "Relative Contributions of Bacteria, Protozoa, and Fungi to In Vitro Degradation of Orchard Grass Cell Walls and Their Interactions". Applied and Environmental Microbiology 66, nr 9 (1.09.2000): 3807–13. http://dx.doi.org/10.1128/aem.66.9.3807-3813.2000.
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ABSTRACT To assess the relative contributions of microbial groups (bacteria, protozoa, and fungi) in rumen fluids to the overall process of plant cell wall digestion in the rumen, representatives of these groups were selected by physical and chemical treatments of whole rumen fluid and used to construct an artificial rumen ecosystem. Physical treatments involved homogenization, centrifugation, filtration, and heat sterilization. Chemical treatments involved the addition of antibiotics and various chemicals to rumen fluid. To evaluate the potential activity and relative contribution to degradation of cell walls by specific microbial groups, the following fractions were prepared: a positive system (whole ruminal fluid), a bacterial (B) system, a protozoal (P) system, a fungal (F) system, and a negative system (cell-free rumen fluid). To assess the interactions between specific microbial fractions, mixed cultures (B+P, B+F, and P+F systems) were also assigned. Patterns of degradation due to the various treatments resulted in three distinct groups of data based on the degradation rate of cell wall material and on cell wall-degrading enzyme activities. The order of degradation was as follows: positive and F systems > B system > negative and P systems. Therefore, fungal activity was responsible for most of the cell wall degradation. Cell wall degradation by the anaerobic bacterial fraction was significantly less than by the fungal fraction, and the protozoal fraction failed to grow under the conditions used. In general, in the mixed culture systems the coculture systems demonstrated a decrease in cellulolysis compared with that of the monoculture systems. When one microbial fraction was associated with another microbial fraction, two types of results were obtained. The protozoal fraction inhibited cellulolysis of cell wall material by both the bacterial and the fungal fractions, while in the coculture between the bacterial fraction and the fungal fraction a synergistic interaction was detected.
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Lee, KE, i CE Pankhurst. "Soil organisms and sustainable productivity". Soil Research 30, nr 6 (1992): 855. http://dx.doi.org/10.1071/sr9920855.
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The soil is a habitat for a vast, complex and interactive community of soil organisms whose activities largely determine the chemical and physical properties of the soil. In a fertile soil the soil biota may have a biomass exceeding 20 t ha-1, with life forms ranging from microscopic bacteria to the largest of earthworms which may be 1 m in length. Only a small fraction, probably <20%, of the soil microflora and microfauna (including bacteria, fungi, algae, protozoa, nematodes, collembola, acari) have been described. The role of soil organisms in the development and maintenance of soil structure, in nutrient cycling and in their various interactions (including associative, harmful and beneficial) with plant roots is described. Trophic interactions between soil organism groups in developed agroecosystems are considered in relation to nutrient cycling and the impact such interactions have on populations of saprophytic, parasitic and symbiotic microorganisms. Prospects for the management of the soil biota to promote sustainable productivity are illustrated by describing the effects of tillage on the composition of soil organism communities. Management technologies that conserve the biodiversity of communities may provide the greatest benefits for the long term sustainability of the soil resource.
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Kodio, Aly, Estelle Menu i Stéphane Ranque. "Eukaryotic and Prokaryotic Microbiota Interactions". Microorganisms 8, nr 12 (17.12.2020): 2018. http://dx.doi.org/10.3390/microorganisms8122018.
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The nature of the relationship between the communities of microorganisms making up the microbiota in and on a host body has been increasingly explored in recent years. Microorganisms, including bacteria, archaea, viruses, parasites and fungi, have often long co-evolved with their hosts. In human, the structure and diversity of microbiota vary according to the host’s immunity, diet, environment, age, physiological and metabolic status, medical practices (e.g., antibiotic treatment), climate, season and host genetics. The recent advent of next generation sequencing (NGS) technologies enhanced observational capacities and allowed for a better understanding of the relationship between distinct microorganisms within microbiota. The interaction between the host and their microbiota has become a field of research into microorganisms with therapeutic and preventive interest for public health applications. This review aims at assessing the current knowledge on interactions between prokaryotic and eukaryotic communities. After a brief description of the metagenomic methods used in the studies were analysed, we summarise the findings of available publications describing the interaction between the bacterial communities and protozoa, helminths and fungi, either in vitro, in experimental models, or in humans. Overall, we observed the existence of a beneficial effect in situations where some microorganisms can improve the health status of the host, while the presence of other microorganisms has been associated with pathologies, resulting in an adverse effect on human health.
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Halsey, Jennifer L. "Current Approaches to the Treatment of Gastrointestinal Infections: Focus on Nitazoxanide". Clinical Medicine. Therapeutics 1 (styczeń 2009): CMT.S2297. http://dx.doi.org/10.4137/cmt.s2297.
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Nitazoxanide is a broad-spectrum agent active against several protozoa, helminths, and bacteria, including C. difficile and H. pylori. It is available as an oral tablet and suspension, both with adequate bioavailability. Nitazoxanide is associated with minimal side effects, has an acceptable safety profile, and has been classified as a pregnancy category B agent. It is 99% protein bound, which could result in drug interactions. It is the preferred agent for the treatment of Cryptospordiosis and Giardiasis in immunocompetent patients and has shown promise for the treatment of rotavirus, mild to moderate initial C. difficile infection, refractory C. difficile infection, Amoebiasis, Blastocystosis, and Taenia saginata.
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Shimeta, Jeff, i Perran L. M. Cook. "Testing assumptions of the eukaryotic inhibitor method for investigating interactions between aquatic protozoa and bacteria, applied to marine sediment". Limnology and Oceanography: Methods 9, nr 7 (lipiec 2011): 288–95. http://dx.doi.org/10.4319/lom.2011.9.288.
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Mampel, Jörg, Thomas Spirig, Stefan S. Weber, Janus A. J. Haagensen, Søren Molin i Hubert Hilbi. "Planktonic Replication Is Essential for Biofilm Formation by Legionella pneumophila in a Complex Medium under Static and Dynamic Flow Conditions". Applied and Environmental Microbiology 72, nr 4 (kwiecień 2006): 2885–95. http://dx.doi.org/10.1128/aem.72.4.2885-2895.2006.
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ABSTRACT Legionella pneumophila persists for a long time in aquatic habitats, where the bacteria associate with biofilms and replicate within protozoan predators. While L. pneumophila serves as a paradigm for intracellular growth within protozoa, it is less clear whether the bacteria form or replicate within biofilms in the absence of protozoa. In this study, we analyzed surface adherence of and biofilm formation by L. pneumophila in a rich medium that supported axenic replication. Biofilm formation by the virulent L. pneumophila strain JR32 and by clinical and environmental isolates was analyzed by confocal microscopy and crystal violet staining. Strain JR32 formed biofilms on glass surfaces and upright polystyrene wells, as well as on pins of “inverse” microtiter plates, indicating that biofilm formation was not simply due to sedimentation of the bacteria. Biofilm formation by an L. pneumophila fliA mutant lacking the alternative sigma factor σ28 was reduced, which demonstrated that bacterial factors are required. Accumulation of biomass coincided with an increase in the optical density at 600 nm and ceased when the bacteria reached the stationary growth phase. L. pneumophila neither grew nor formed biofilms in the inverse system if the medium was exchanged twice a day. However, after addition of Acanthamoeba castellanii, the bacteria proliferated and adhered to surfaces. Sessile (surface-attached) and planktonic (free-swimming) L. pneumophila expressed β-galactosidase activity to similar extents, and therefore, the observed lack of proliferation of surface-attached bacteria was not due to impaired protein synthesis or metabolic activity. Cocultivation of green fluorescent protein (GFP)- and DsRed-labeled L. pneumophila led to randomly interspersed cells on the substratum and in aggregates, and no sizeable patches of clonally growing bacteria were observed. Our findings indicate that biofilm formation by L. pneumophila in a rich medium is due to growth of planktonic bacteria rather than to growth of sessile bacteria. In agreement with this conclusion, GFP-labeled L. pneumophila initially adhered in a continuous-flow chamber system but detached over time; the detachment correlated with the flow rate, and there was no accumulation of biomass. Under these conditions, L. pneumophila persisted in biofilms formed by Empedobacter breve or Microbacterium sp. but not in biofilms formed by Klebsiella pneumoniae or other environmental bacteria, suggesting that specific interactions between the bacteria modulate adherence.
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Belén-Chaar, Florencia, Jimena Pía-Fernández, Lucas-R. Sepúlveda i Tamara Rubilar. "The influence of density on survival and larval development in the sea urchin Arbacia dufresnii (Echinodermata: Echinoidea)". Revista de Biología Tropical 69, Suppl.1 (23.03.2021): 334–45. http://dx.doi.org/10.15517/rbt.v69isuppl.1.46365.
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Introduction: Density is one of the critical factors in echinoderm larvae for aquaculture purposes. Echinoplutei larvae are very sensitive to overcrowding. High culture density can lead to problems with bacteria or protozoa, decreasing survival and generating abnormal morphotypes. Objective: To evaluate the effect of culture density on survival and larval growth in the sea urchin Arbacia dufresnii. Methods: Two days after fertilization of A. dufresnii we we kept treatments at 1, 3, 5 and 10 larvae.ml-1, with three replicates each. We recorded survival and abnormal morphotypes periodically, as well as growth:somatic rod length, total length, and length of the post oral arms,. we applied generalized linear models. Results: Survival is dependent on density, time and replicates, and their interactions. Larval growth depended on density and time, also with interaction between the variables. The treatment of 5 larvae.ml-1 had the highest survival and larval condition. Conclusions: Larval culture of A. dufresnii had the best results at 5 larvae.ml-1.
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Rico, D. E., S. H. Preston, J. M. Risser i K. J. Harvatine. "Rapid changes in key ruminal microbial populations during the induction of and recovery from diet-induced milk fat depression in dairy cows". British Journal of Nutrition 114, nr 3 (30.06.2015): 358–67. http://dx.doi.org/10.1017/s0007114515001865.
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The ruminant provides a powerful model for understanding the temporal dynamics of gastrointestinal microbial communities. Diet-induced milk fat depression (MFD) in the dairy cow is caused by rumen-derived bioactive fatty acids, and is commonly attributed to the changes in the microbial population. The aim of the present study was to determine the changes occurring in nine ruminal bacterial taxa with well-characterised functions, and abundance of total fungi, ciliate protozoa and bacteria during the induction of and recovery from MFD. Interactions between treatment and time were observed for ten of the twelve populations. The total number of both fungi and ciliate protozoa decreased rapidly (days 4 and 8, respectively) by more than 90 % during the induction period and increased during the recovery period. The abundance ofStreptococcus bovis(amylolytic) peaked at 350 % of control levels on day 4 of induction and rapidly decreased during the recovery period. The abundance ofPrevotella bryantii(amylolytic) decreased by 66 % from day 8 to 20 of the induction period and increased to the control levels on day 12 of the recovery period. The abundance ofMegasphaera elsdeniiandSelenomonas ruminantium(lactate-utilising bacteria) increased progressively until day 12 of induction (>170 %) and decreased during the recovery period. The abundance ofFibrobacter succinogenes(fibrolytic) decreased by 97 % on day 4 of induction and increased progressively to an equal extent during the recovery period, although smaller changes were observed for other fibrolytic bacteria. The abundance of theButyrivibrio fibrisolvens/Pseudobutyrivibriogroup decreased progressively during the induction period and increased during the recovery period, whereas the abundance ofButyrivibrio hungateiwas not affected by treatment. Responsive taxa were modified rapidly, with the majority of changes occurring within 8 d and their time course was similar to the time course of the induction of MFD, demonstrating a strong correlation between changes in ruminal microbial populations and MFD.
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BUZA, Victoria, Maria Catalina MATEI i Laura Cristina STEFANUT. "Intestinal Ecosystem: Interaction and Coexistence Between “Parasitome” and Microbial Communities". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Veterinary Medicine 77, nr 1 (3.06.2020): 15. http://dx.doi.org/10.15835/buasvmcn-vm:2019.0032.
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The vertebrate gut has been continuously populated with complex and dynamic microbial and eukaryotic communities, that over millions of years have coevolved both spatially and temporally (Kreisinger et al., 2015). Due to the prolonged coexistence, intestinal parasites (protozoa and helminths) and resident microbiota have developed the ability to influence one another by several mechanisms: 1) produce changes at the level of intestinal mucus and epithelial barrier, 2) alter the host immune response or 3) direct interaction (Leung et al., 2018). The uncontrolled use of anthelmintics can lead to the elimination of commensal organisms and alteration of host immunity and intestinal microbial community composition. Thus, the aim of this research is to highlight the complexity of interactions between intestinal bacteria and parasites and their importance for the host. The “parasitome”- microbiota relationship is a complex phenomenon that plays an essential role in host intestinal homeostasis, the absence or alteration of either of these organisms being able to cause a severe disruption of host immune system (Leung et al., 2018). Is therefore essential to acquire a deeper understanding of the molecular mechanisms of interaction between these two communities.
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Tisserant, Constance, i Arne Weiberg. "Extracellular vesicles in plant host-microbe interaction". How cells communicate - an introduction to extracellular vesicles 1, nr 1 (28.11.2019): 46–50. http://dx.doi.org/10.47184/tev.2019.01.07.
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Extracellular vesicles (EVs) are secreted lipid bilayer membrane particles that are increasingly drawing attention due to their potential role in intercellular communication. EVs have been mainly reported in mammalian systems, but are also found in non-mammalian classes, such as Archeae, bacteria, fungi, oomycetes, protozoa, invertebrates and plants. Over the last decade, EV research on mammalian systems has been massively advanced driven by the interests and applications of the biomedical field, while research on non-mammalian EVs that aims to understand the biological origins and functions of EVs remains rather descriptive and premature. Nevertheless, recent pioneering works resulted in novel concepts that place EVs carrying regulatory small RNAs as central players in inter-species and cross-kingdom communication with emphasis on host-pathogen, host-parasite and host-microbiome interactions. EVs transport small RNAs from microbe/pathogen/parasite to animal or plant hosts, and vice versa, which results in the manipulation of host immunity or microbial virulence, respectively. This article highlights some of the latest discoveries regarding EV-mediated communication across species and kingdoms with a special focus on plants and their interacting microbes.
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Burzyńska, Patrycja, Łukasz F. Sobala, Krzysztof Mikołajczyk, Marlena Jodłowska i Ewa Jaśkiewicz. "Sialic Acids as Receptors for Pathogens". Biomolecules 11, nr 6 (2.06.2021): 831. http://dx.doi.org/10.3390/biom11060831.
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Carbohydrates have long been known to mediate intracellular interactions, whether within one organism or between different organisms. Sialic acids (Sias) are carbohydrates that usually occupy the terminal positions in longer carbohydrate chains, which makes them common recognition targets mediating these interactions. In this review, we summarize the knowledge about animal disease-causing agents such as viruses, bacteria and protozoa (including the malaria parasite Plasmodium falciparum) in which Sias play a role in infection biology. While Sias may promote binding of, e.g., influenza viruses and SV40, they act as decoys for betacoronaviruses. The presence of two common forms of Sias, Neu5Ac and Neu5Gc, is species-specific, and in humans, the enzyme converting Neu5Ac to Neu5Gc (CMAH, CMP-Neu5Ac hydroxylase) is lost, most likely due to adaptation to pathogen regimes; we discuss the research about the influence of malaria on this trait. In addition, we present data suggesting the CMAH gene was probably present in the ancestor of animals, shedding light on its glycobiology. We predict that a better understanding of the role of Sias in disease vectors would lead to more effective clinical interventions.
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Torrecilhas, Ana Claudia, Patricia Xander, Karen Spadari Ferreira i Wagner Luiz Batista. "Alternative Host Models for Testing Anti-Protozoal or Antifungal Compounds and Fungal Infection". Current Topics in Medicinal Chemistry 18, nr 4 (29.05.2018): 300–311. http://dx.doi.org/10.2174/1568026618666180412154519.
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The neglected tropical diseases (NTDs) are caused by several parasites, fungi, bacteria and viruses and affect more than one billion people in the world. The control and prevention against NTDs need implementation of alternative methods for testing new compounds against these diseases. For the implementation of alternative methods, it is necessary to apply the principles of replacement, reduction and refinement (the 3Rs) for the use of laboratory animals. Accordingly, the present review addressed a variety of alternative models to study the infections caused by protozoa and fungi. Overall, vertebrate and invertebrate models of fungal infection have been used to elucidate host-pathogen interactions. However, until now the insect model has not been used in protozoal studies as an alternative method, but there is interest in the scientific community to try new tools to screen alternative drugs to control and prevent protozoal infections.
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Mazalovska, Milena, i J. Calvin Kouokam. "Lectins as Promising Therapeutics for the Prevention and Treatment of HIV and Other Potential Coinfections". BioMed Research International 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/3750646.
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Human immunodeficiency virus-acquired immunodeficiency syndrome (HIV/AIDS) remains a global health problem. Current therapeutics specifically target the viral pathogen at various stages of its life cycle, although complex interactions between HIV and other pathogenic organisms are evident. Targeting HIV and concomitant infectious pathogens simultaneously, both by therapeutic regimens and in prevention strategies, would help contain the AIDS pandemic. Lectins, a ubiquitous group of proteins that specifically bind glycosylated molecules, are interesting compounds that could be used for this purpose, with demonstrated anti-HIV properties. In addition, potential coinfecting pathogens, including other enveloped viruses, bacteria, yeasts and fungi, and protozoa, display sugar-coated macromolecules on their surfaces, making them potential targets of lectins. This review summarizes the currently available findings suggesting that lectins should be further developed to simultaneously fight the AIDS pandemic and concomitant infections in HIV infected individuals.
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Kgopa, Pholosho Mmmateko, Phatu William Mashela i Alen Manyevere. "Microbial Quality of Treated Wastewater and Borehole Water Used for Irrigation in a Semi-Arid Area". International Journal of Environmental Research and Public Health 18, nr 16 (23.08.2021): 8861. http://dx.doi.org/10.3390/ijerph18168861.
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The current study investigated the distribution of microbial populations and diversity in treated wastewater used for irrigation at the University of Limpopo Experimental Farm (ULEF), from different stages of post treatment disposal at Mankweng Wastewater Treatment Plant (MWTP) in Limpopo Province, South Africa. The study was arranged in a 4 × 5 factorial experiment, which studied the interactive effects of four collection points and five months of sampling, with borehole water used as a reference point. Water samples were analyzed for bacteria, helminths, and protozoa. All data were transformed and subjected to factorial analysis of variance. The site–time interactions were significant for Salmonella spp. and Ascaris lumbricoides, whereas collection point was significant for all variables. In conclusion, movement and storage of water post treatment at MWTP were able to improve the microbial quality of the treated wastewater disposed for irrigation at ULEF.
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FENTON, ANDY. "Dances with worms: the ecological and evolutionary impacts of deworming on coinfecting pathogens". Parasitology 140, nr 9 (29.05.2013): 1119–32. http://dx.doi.org/10.1017/s0031182013000590.
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SUMMARYParasitic helminths are ubiquitous in most host, including human, populations. Helminths often alter the likelihood of infection and disease progression of coinfecting microparasitic pathogens (viruses, bacteria, protozoa), and there is great interest in incorporating deworming into control programmes for many major diseases (e.g. HIV, tuberculosis, malaria). However, such calls are controversial; studies show the consequences of deworming for the severity and spread of pathogens to be highly variable. Hence, the benefits of deworming, although clear for reducing the morbidity due to helminth infection per se, are unclear regarding the outcome of coinfections and comorbidities. I develop a theoretical framework to explore how helminth coinfection with other pathogens affects host mortality and pathogen spread and evolution under different interspecific parasite interactions. In all cases the outcomes of coinfection are highly context-dependent, depending on the mechanism of helminth-pathogen interaction and the quantitative level of helminth infection, with the effects of deworming potentially switching from beneficial to detrimental depending on helminth burden. Such context-dependency may explain some of the variation in the benefits of deworming seen between studies, and highlights the need for obtaining a quantitative understanding of parasite interactions across realistic helminth infection ranges. However, despite this complexity, this framework reveals predictable patterns in the effects of helminths that may aid the development of more effective, integrated management strategies to combat pathogens in this coinfected world.
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Jousset, Alexandre, Laur�ne Rochat, Stefan Scheu, Michael Bonkowski i Christoph Keel. "Predator-Prey Chemical Warfare Determines the Expression of Biocontrol Genes by Rhizosphere-Associated Pseudomonas fluorescens". Applied and Environmental Microbiology 76, nr 15 (4.06.2010): 5263–68. http://dx.doi.org/10.1128/aem.02941-09.
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ABSTRACT Soil bacteria are heavily consumed by protozoan predators, and many bacteria have evolved defense strategies such as the production of toxic exometabolites. However, the production of toxins is energetically costly and therefore is likely to be adjusted according to the predation risk to balance the costs and benefits of predator defense. We investigated the response of the biocontrol bacterium Pseudomonas fluorescens CHA0 to a common predator, the free-living amoeba Acanthamoeba castellanii. We monitored the effect of the exposure to predator cues or direct contact with the predators on the expression of the phlA, prnA, hcnA, and pltA genes, which are involved in the synthesis of the toxins, 2,4-diacetylphloroglucinol (DAPG), pyrrolnitrin, hydrogen cyanide, and pyoluteorin, respectively. Predator chemical cues led to 2.2-, 2.0-, and 1.2-fold increases in prnA, phlA, and hcnA expression, respectively, and to a 25% increase in bacterial toxicity. The upregulation of the tested genes was related to the antiprotozoan toxicity of the corresponding toxins. Pyrrolnitrin and DAPG had the highest toxicity, suggesting that bacteria secrete a predator-specific toxin cocktail. The response of the bacteria was elicited by supernatants of amoeba cultures, indicating that water-soluble chemical compounds were responsible for induction of the bacterial defense response. In contrast, direct contact of bacteria with living amoebae reduced the expression of the four bacterial toxin genes by up to 50%, suggesting that protozoa can repress bacterial toxicity. The results indicate that predator-prey interactions are a determinant of toxin production by rhizosphere P. fluorescens and may have an impact on its biocontrol potential.
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Cabezas-Cruz, Alejandro, Adnan Hodžić, Lourdes Mateos-Hernández, Marinela Contreras i José de la Fuente. "Tick–human interactions: from allergic klendusity to the α-Gal syndrome". Biochemical Journal 478, nr 9 (14.05.2021): 1783–94. http://dx.doi.org/10.1042/bcj20200915.
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Ticks and the pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. The ability of some animal species to acquire resistance to blood-feeding by ticks after a single or repeated infestation is known as acquired tick resistance (ATR). This resistance has been associated to tick-specific IgE response, the generation of skin-resident memory CD4+ T cells, basophil recruitment, histamine release, and epidermal hyperplasia. ATR has also been associated with protection to tick-borne tularemia through allergic klendusity, a disease-escaping ability produced by the development of hypersensitivity to an allergen. In addition to pathogen transmission, tick infestation in humans is associated with the α-Gal syndrome (AGS), a type of allergy characterized by an IgE response against the carbohydrate Galα1-3Gal (α-Gal). This glycan is present in tick salivary proteins and on the surface of tick-borne pathogens such as Borrelia burgdorferi and Anaplasma phagocytophilum, the causative agents of Lyme disease and granulocytic anaplasmosis. Most α-Gal-sensitized individuals develop IgE specific against this glycan, but only a small fraction develop the AGS. This review summarizes our current understanding of ATR and its impact on the continuum α-Gal sensitization, allergy, and the AGS. We propose that the α-Gal-specific IgE response in humans is an evolutionary adaptation associated with ATR and allergic klendusity with the trade-off of developing AGS.
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Allegra, Alessandro, Caterina Musolino, Alessandro Tonacci, Giovanni Pioggia i Sebastiano Gangemi. "Interactions between the MicroRNAs and Microbiota in Cancer Development: Roles and Therapeutic Opportunities". Cancers 12, nr 4 (27.03.2020): 805. http://dx.doi.org/10.3390/cancers12040805.
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The human microbiota is made up of the fungi, bacteria, protozoa and viruses cohabiting within the human body. An altered microbiota can provoke diseases such as cancer. The mechanisms by which a modified microbiota can intervene in the onset and progression of neoplastic diseases are manifold. For instance, these include the effects on the immune system and the onset of obesity. A different mechanism seems to be constituted by the continuous and bidirectional relationships existing between microbiota and miRNAs. MiRNAs emerged as a novel group of small endogenous non-coding RNAs from that control gene expression. Several works seem to confirm the presence of a close connection between microbiota and miRNAs. Although the main literature data concern the correlations between microbiota, miRNAs and colon cancer, several researches have revealed the presence of connections with other types of tumour, including the ovarian tumour, cervical carcinoma, hepatic carcinoma, neoplastic pathologies of the central nervous system and the possible implication of the microbiota-miRNAs system on the response to the treatment of neoplastic pathologies. In this review, we summarise the physiological and pathological functions of the microbiota on cancer onset by governing miRNA production. A better knowledge of the bidirectional relationships existing between microbiota and miRNAs could provide new markers for the diagnosis, staging and monitoring of cancer and seems to be a promising approach for antagomir-guided approaches as therapeutic agents.
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Bjørnlund, Lisa, Flemming Ekelund, Søren Christensen, Carsten Suhr Jacobsen, Paul Henning Krogh i Kaare Johnsen. "Interactions between saprotrophic fungi, bacteria and protozoa on decomposing wheat roots in soil influenced by the fungicide fenpropimorph (Corbel®): a field study". Soil Biology and Biochemistry 32, nr 7 (lipiec 2000): 967–75. http://dx.doi.org/10.1016/s0038-0717(00)00005-5.
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Nuttall, P. A. "Displaced tick-parasite interactions at the host interface". Parasitology 116, S1 (1998): S65—S72. http://dx.doi.org/10.1017/s003118200008495x.
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SummaryReciprocal interactions of parasites transmitted by blood-sucking arthropod vectors have been studied primarily at the parasite–host and parasite–vector interface. The third component of this parasite triangle, the vector–host interface, has been largely ignored. Now there is growing realization that reciprocal interactions between arthropod vectors and their vertebrate hosts play a pivotal role in the survival of arthropod-borne viruses, bacteria, and protozoa. The vector–host interface is the site where the haematophagous arthropod feeds. To obtain a blood meal, the vector must overcome the host's inflammatory, haemostatic, and immune responses. This problem is greatest for ixodid ticks which may imbibe as much as 15 ml blood whilst continuously attached to their host for 10 days or more. To feed successfully, the interface between tick and host becomes a battle between the host's mechanisms for combating the tick and the tick's armoury of bioactive proteins and other chemicals which it secretes, via saliva, into the feeding lesion formed in the host's skin. Parasites entering this battlefield encounter a privileged site in their vertebrate host that has been profoundly modified by the pharmacological activities of their vector's saliva. For example, ticks suppress natural killer cells and interferons, both of which have potent antiviral activities. Not surprisingly, vector-borne parasites exploit the immunomodulated feeding site to promote their transmission and infection. Certain tick-borne viruses are so successful at this that they are transmitted from one infected tick, through the vertebrate host to a co-feeding uninfected tick, without a detectable viraemia (virus circulating in the host's blood), and with no untoward effect on the host. When such viruses do have an adverse effect on the host, they may impede their vectors' feeding. Thus important interactions between ticks and tick-borne parasites are displaced to the interface with their vertebrate host - the skin site of blood-feeding and infection.
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Rutherford, P. M., i N. G. Juma. "Simulation of protozoa-induced mineralization of bacterial carbon and nitrogen". Canadian Journal of Soil Science 72, nr 3 (1.08.1992): 201–16. http://dx.doi.org/10.4141/cjss92-020.
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Modelling in soil ecological research is a means of linking the dynamics of microbial and faunal populations to soil processes. The objectives of this study were (i) to simulate bacterial-protozoan interactions and flows of C and N in clay loam Orthic Black Chernozemic soil under laboratory condtions; and (ii) to quantify the flux of C and N (inputs and outputs) through various pools using the simulation model. The unique features of this model are: (i) it combines the food chain with specific soil C and N pools, and (ii) it simultaneously traces the flows of C, 14C, N and 15N. It was possible to produce a model that fitted the data observed for the soil. The simulated CO2-C evolved during the first 12 d was due mainly to glucose addition (171 μg C g−1 soil) and cycling of C in the soil (160 μg C g−1 soil). During this interval, bacterial C uptake was 5.5-fold greater than the initial bacterial C pool size. In the first 12 d protozoa directly increased total CO2-C evolution by 11% and increased NH4-N mineralization 3-fold, compared to soil containing only bacteria. Mineralization of C and N was rapid when bacterial numbers were increased as a result of glucose addition. Key words: Acanthamoeba sp., modelling, N mineralization-immobilization, organic matter, Pseudomonas sp., Typic Cryoboroll
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Weber, Roy E., i Serge N. Vinogradov. "Nonvertebrate Hemoglobins: Functions and Molecular Adaptations". Physiological Reviews 81, nr 2 (1.04.2001): 569–628. http://dx.doi.org/10.1152/physrev.2001.81.2.569.
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Hemoglobin (Hb) occurs in all the kingdoms of living organisms. Its distribution is episodic among the nonvertebrate groups in contrast to vertebrates. Nonvertebrate Hbs range from single-chain globins found in bacteria, algae, protozoa, and plants to large, multisubunit, multidomain Hbs found in nematodes, molluscs and crustaceans, and the giant annelid and vestimentiferan Hbs comprised of globin and nonglobin subunits. Chimeric hemoglobins have been found recently in bacteria and fungi. Hb occurs intracellularly in specific tissues and in circulating red blood cells (RBCs) and freely dissolved in various body fluids. In addition to transporting and storing O2and facilitating its diffusion, several novel Hb functions have emerged, including control of nitric oxide (NO) levels in microorganisms, use of NO to control the level of O2in nematodes, binding and transport of sulfide in endosymbiont-harboring species and protection against sulfide, scavenging of O2in symbiotic leguminous plants, O2sensing in bacteria and archaebacteria, and dehaloperoxidase activity useful in detoxification of chlorinated materials. This review focuses on the extensive variation in the functional properties of nonvertebrate Hbs, their O2binding affinities, their homotropic interactions (cooperativity), and the sensitivities of these parameters to temperature and heterotropic effectors such as protons and cations. Whenever possible, it attempts to relate the ligand binding properties to the known molecular structures. The divergent and convergent evolutionary trends evident in the structures and functions of nonvertebrate Hbs appear to be adaptive in extending the inhabitable environment available to Hb-containing organisms.
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Aluthge, Nirosh D., Dana M. Van Sambeek, Erin E. Carney-Hinkle, Yanshuo S. Li, Samodha C. Fernando i Thomas E. Burkey. "BOARD INVITED REVIEW: The pig microbiota and the potential for harnessing the power of the microbiome to improve growth and health1". Journal of Animal Science 97, nr 9 (28.06.2019): 3741–57. http://dx.doi.org/10.1093/jas/skz208.
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Abstract A variety of microorganisms inhabit the gastrointestinal tract of animals including bacteria, archaea, fungi, protozoa, and viruses. Pioneers in gut microbiology have stressed the critical importance of diet:microbe interactions and how these interactions may contribute to health status. As scientists have overcome the limitations of culture-based microbiology, the importance of these interactions has become more clear even to the extent that the gut microbiota has emerged as an important immunologic and metabolic organ. Recent advances in metagenomics and metabolomics have helped scientists to demonstrate that interactions among the diet, the gut microbiota, and the host to have profound effects on animal health and disease. However, although scientists have now accumulated a great deal of data with respect to what organisms comprise the gastrointestinal landscape, there is a need to look more closely at causative effects of the microbiome. The objective of this review is intended to provide: 1) a review of what is currently known with respect to the dynamics of microbial colonization of the porcine gastrointestinal tract; 2) a review of the impact of nutrient:microbe effects on growth and health; 3) examples of the therapeutic potential of prebiotics, probiotics, and synbiotics; and 4) a discussion about what the future holds with respect to microbiome research opportunities and challenges. Taken together, by considering what is currently known in the four aforementioned areas, our overarching goal is to set the stage for narrowing the path towards discovering how the porcine gut microbiota (individually and collectively) may affect specific host phenotypes.
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Wiciński, Michał, Ewelina Sawicka, Jakub Gębalski, Karol Kubiak i Bartosz Malinowski. "Human Milk Oligosaccharides: Health Benefits, Potential Applications in Infant Formulas, and Pharmacology". Nutrients 12, nr 1 (20.01.2020): 266. http://dx.doi.org/10.3390/nu12010266.
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The first months of life are a special time for the health development and protection of infants. Breastfeeding is the natural and best way of feeding an infant, and positively influences their development and health. Breast milk provides the ideal balance of nutrients for the infant and contains countless bioactive ingredients such as immunoglobulins, hormones, oligosaccharides and others. Human milk oligosaccharides (HMOs) are a very important and interesting constituent of human milk, and are the third most abundant solid component after lactose and lipids. They are a structurally and biologically diverse group of complex indigestible sugars. This article will discuss the mechanisms of action of HMOs in infants, such as their anti-adhesive properties, properties modulating the immune system, and impact on bacterial flora development. Many health benefits result from consuming HMOs. They also may decrease the risk of infection by their interactions with viruses, bacteria or protozoa. The commercial use of HMOs in infant formula, future directions, and research on the use of HMOs as a therapy will be discussed.
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Korajkic, Asja, Pauline Wanjugi i Valerie J. Harwood. "Indigenous Microbiota and Habitat Influence Escherichia coli Survival More than Sunlight in Simulated Aquatic Environments". Applied and Environmental Microbiology 79, nr 17 (28.06.2013): 5329–37. http://dx.doi.org/10.1128/aem.01362-13.
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ABSTRACTThe reported fate ofEscherichia coliin the environment ranges from extended persistence to rapid decline. Incomplete understanding of factors that influence survival hinders risk assessment and modeling of the fate of fecal indicator bacteria (FIB) and pathogens. FIB persistence in subtropical aquatic environments was explored in outdoor mesocosms inoculated with fiveE. colistrains. The manipulated environmental factors were (i) presence or absence of indigenous microbiota (attained by natural, disinfected, and cycloheximide treatments), (ii) freshwater versus seawater, and (iii) water column versus sediment matrices. When indigenous microbes were removed (disinfected),E. coliconcentrations decreased little despite exposure to sunlight. Conversely, under conditions that included the indigenous microbiota (natural), significantly greater declines inE. colioccurred regardless of the habitat. The presence of indigenous microbiota and matrix significantly influencedE. colidecline, but their relative importance differed in freshwater versus seawater. Cycloheximide, which inhibits protein synthesis in eukaryotes, significantly diminished the magnitude ofE. colidecline in water but not in sediments. The inactivation of protozoa and bacterial competitors (disinfected) caused a greater decline inE. colithan cycloheximide alone in water and sediments. These results indicate that the autochthonous microbiota are an important contributor to the decline ofE. coliin fresh and seawater subtropical systems, but their relative contribution is habitat dependent. This work advances our understanding of how interactions with autochthonous microbiota influence the fate ofE. coliin aquatic environments and provides the framework for studies of the ecology of enteric pathogens and other allochthonous bacteria in similar environments.
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Lane, Nick. "The unseen world: reflections on Leeuwenhoek (1677) ‘Concerning little animals’". Philosophical Transactions of the Royal Society B: Biological Sciences 370, nr 1666 (19.04.2015): 20140344. http://dx.doi.org/10.1098/rstb.2014.0344.
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Leeuwenhoek's 1677 paper, the famous ‘letter on the protozoa’, gives the first detailed description of protists and bacteria living in a range of environments. The colloquial, diaristic style conceals the workings of a startlingly original experimental mind. Later scientists could not match the resolution and clarity of Leeuwenhoek's microscopes, so his discoveries were doubted or even dismissed over the following centuries, limiting their direct influence on the history of biology; but work in the twentieth century confirmed Leeuwenhoek's discovery of bacterial cells, with a resolution of less than 1 µm. Leeuwenhoek delighted most in the forms, interactions and behaviour of his little ‘animalcules', which inhabited a previously unimagined microcosmos. In these reflections on the scientific reach of Leeuwenhoek's ideas and observations, I equate his questions with the preoccupations of our genomic era: what is the nature of Leeuwenhoek's animalcules, where do they come from, how do they relate to each other? Even with the powerful tools of modern biology, the answers are far from resolved—these questions still challenge our understanding of microbial evolution. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society .
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Sciuto, Emanuele Luigi, Pasqualina Laganà, Simona Filice, Silvia Scalese, Sebania Libertino, Domenico Corso, Giuseppina Faro i Maria Anna Coniglio. "Environmental Management of Legionella in Domestic Water Systems: Consolidated and Innovative Approaches for Disinfection Methods and Risk Assessment". Microorganisms 9, nr 3 (11.03.2021): 577. http://dx.doi.org/10.3390/microorganisms9030577.
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Legionella is able to remain in water as free-living planktonic bacteria or to grow within biofilms that adhere to the pipes. It is also able to enter amoebas or to switch into a viable but not culturable (VBNC) state, which contributes to its resistance to harsh conditions and hinders its detection in water. Factors regulating Legionella growth, such as environmental conditions, type and concentration of available organic and inorganic nutrients, presence of protozoa, spatial location of microorganisms, metal plumbing components, and associated corrosion products are important for Legionella survival and growth. Finally, water treatment and distribution conditions may affect each of these factors. A deeper comprehension of Legionella interactions in water distribution systems with the environmental conditions is needed for better control of the colonization. To this purpose, the implementation of water management plans is the main prevention measure against Legionella. A water management program requires coordination among building managers, health care providers, and Public Health professionals. The review reports a comprehensive view of the state of the art and the promising perspectives of both monitoring and disinfection methods against Legionella in water, focusing on the main current challenges concerning the Public Health sector.
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Tartaglia, Maria, Felipe Bastida, Rosaria Sciarrillo i Carmine Guarino. "Soil Metaproteomics for the Study of the Relationships Between Microorganisms and Plants: A Review of Extraction Protocols and Ecological Insights". International Journal of Molecular Sciences 21, nr 22 (11.11.2020): 8455. http://dx.doi.org/10.3390/ijms21228455.
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Soil is a complex matrix where biotic and abiotic components establish a still unclear network involving bacteria, fungi, archaea, protists, protozoa, and roots that are in constant communication with each other. Understanding these interactions has recently focused on metagenomics, metatranscriptomics and less on metaproteomics studies. Metaproteomic allows total extraction of intracellular and extracellular proteins from soil samples, providing a complete picture of the physiological and functional state of the “soil community”. The advancement of high-performance mass spectrometry technologies was more rapid than the development of ad hoc extraction techniques for soil proteins. The protein extraction from environmental samples is biased due to interfering substances and the lower amount of proteins in comparison to cell cultures. Soil sample preparation and extraction methodology are crucial steps to obtain high-quality resolution and yields of proteins. This review focuses on the several soil protein extraction protocols to date to highlight the methodological challenges and critical issues for the application of proteomics to soil samples. This review concludes that improvements in soil protein extraction, together with the employment of ad hoc metagenome database, may enhance the identification of proteins with low abundance or from non-dominant populations and increase our capacity to predict functional changes in soil.
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Griffiths, Emily C., Amy B. Pedersen, Andy Fenton i Owen L. Petchey. "Analysis of a summary network of co-infection in humans reveals that parasites interact most via shared resources". Proceedings of the Royal Society B: Biological Sciences 281, nr 1782 (7.05.2014): 20132286. http://dx.doi.org/10.1098/rspb.2013.2286.
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Simultaneous infection by multiple parasite species (viruses, bacteria, helminths, protozoa or fungi) is commonplace. Most reports show co-infected humans to have worse health than those with single infections. However, we have little understanding of how co-infecting parasites interact within human hosts. We used data from over 300 published studies to construct a network that offers the first broad indications of how groups of co-infecting parasites tend to interact. The network had three levels comprising parasites, the resources they consume and the immune responses they elicit, connected by potential, observed and experimentally proved links. Pairs of parasite species had most potential to interact indirectly through shared resources, rather than through immune responses or other parasites. In addition, the network comprised 10 tightly knit groups, eight of which were associated with particular body parts, and seven of which were dominated by parasite–resource links. Reported co-infection in humans is therefore structured by physical location within the body, with bottom-up, resource-mediated processes most often influencing how, where and which co-infecting parasites interact. The many indirect interactions show how treating an infection could affect other infections in co-infected patients, but the compartmentalized structure of the network will limit how far these indirect effects are likely to spread.
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Shah, K. K., S. Tripathi, I. Tiwari, J. Shrestha, B. Modi, N. Paudel i B. D. Das. "Role of soil microbes in sustainable crop production and soil health: A review". Agricultural Science and Technology 13, Volume 13, Issue 2 (czerwiec 2021): 109–18. http://dx.doi.org/10.15547/ast.2021.02.019.
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Abstract. Global food production needs to be increased in order to feed the world’s growing population and at the same time, the reliance on inorganic fertilizers and pesticides should be minimized. To accomplish this goal, the various beneficial associations between plants and soil microorganisms should be explored. The soil microbes are bacteria, actinomycetes, viruses, fungi, nematode, and protozoa. They have an important soil function that has fulfilled several useful tasks in the soil system. Microbes support biological nitrogen fixation of different biological transformations that support the accumulation and utilization of key nutrients, support root and shoot growth processes, disease control, and improve soil quality in crop cultivation. Soil microbes offer nutrient-dense nourishment improved crop production and recycle soil solutions. They play an essential role in decomposing organic matter, cycling nutrients, and fertilizing the soil. Besides, they improve plant growth on various physiological parameters of plants by a number of mechanisms. The mechanism involved in growth promotion includes plant growth regulators, production of different metabolites, and conversion of atmospheric nitrogen into ammonia in direct and indirect ways. In addition, soil microbes offer resistance against diseases. This review outlines the significant impact of soil microbes on sustainable agricultural growth, the benefits of microbes in maintaining soil health, and their interactions.
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FENTON, ANDY. "Editorial: Mathematical modelling of infectious diseases". Parasitology 143, nr 7 (30.03.2016): 801–4. http://dx.doi.org/10.1017/s0031182016000214.
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The field of disease ecology – the study of the spread and impact of parasites and pathogens within their host populations and communities – has a long history of using mathematical models. Dating back over 100 years, researchers have used mathematics to describe the spread of disease-causing agents, understand the relationship between host density and transmission and plan control strategies. The use of mathematical modelling in disease ecology exploded in the late 1970s and early 1980s through the work of Anderson and May (Anderson and May, 1978, 1981, 1992; May and Anderson, 1978), who developed the fundamental frameworks for studying microparasite (e.g. viruses, bacteria and protozoa) and macroparasite (e.g. helminth) dynamics, emphasizing the importance of understanding features such as the parasite's basic reproduction number (R0) and critical community size that form the basis of disease ecology research to this day. Since the initial models of disease population dynamics, which primarily focused on human diseases, theoretical disease research has expanded hugely to encompass livestock and wildlife disease systems, and also to explore evolutionary questions such as the evolution of parasite virulence or drug resistance. More recently there have been efforts to broaden the field still further, to move beyond the standard ‘one-host-one-parasite’ paradigm of the original models, to incorporate many aspects of complexity of natural systems, including multiple potential host species and interactions among multiple parasite species.
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Drago-Serrano, Maria Elisa, Rafael Campos-Rodriguez, Julio Cesar Carrero i Mireya de la Garza. "Lactoferrin and Peptide-derivatives: Antimicrobial Agents with Potential Use in Nonspecific Immunity Modulation". Current Pharmaceutical Design 24, nr 10 (28.05.2018): 1067–78. http://dx.doi.org/10.2174/1381612824666180327155929.
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Lactoferrin (Lf) is a conserved cationic non-heme glycoprotein that is part of the innate immune defense system of mammals. Lf is present in colostrum, milk and mucosal sites, and it is also produced by polymorphonuclear neutrophils and secreted at infection sites. Lf and Lf N-terminus peptide-derivatives named lactoferricins (Lfcins) are molecules with microbiostatic and microbicidal action in a wide array of pathogens. In addition, they display regulatory properties on components of nonspecific immunity, including toll-like receptors, proand anti-inflammatory cytokines, and reactive oxygen species. Mechanisms explaining the ability of Lf and Lfcins to display both up- and down-modulatory properties on cells are not fully understood but result, in part, from their interactions with membrane receptors that elicit biochemical signal pathways, whereas other receptors enable the nuclear translocation of these molecules for the modulation of target genes. The dual role of Lf and Lfcins as antimicrobials and immunomodulators is of biotechnological and pharmaceutical interest. Native Lf and its peptide-derivatives from human and bovine sources, the recombinant versions of the human protein, and their synthetic peptides have potential application as adjunctive agents in therapies to combat infections caused by multi-resistant bacteria and those caused by fungi, protozoa and viruses, as well as in the prevention and reduction of several types of cancer and response to LPS-shock, among other effects. In this review, we summarize the immunomodulatory properties of the unique multifunctional protein Lf and its N-terminus peptides.
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Iebba, Valerio, Floriana Santangelo, Valentina Totino, Fabrizio Pantanella, Anatole Monsia, Veronica Di Cristanziano, David Di Cave, Serena Schippa, Federica Berrilli i Rossella D'Alfonso. "Gut microbiota related to Giardia duodenalis, Entamoeba spp. and Blastocystis hominis infections in humans from Côte d’Ivoire". Journal of Infection in Developing Countries 10, nr 09 (30.09.2016): 1035–41. http://dx.doi.org/10.3855/jidc.8179.
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Introduction: Literature data provide little information about protozoa infections and gut microbiota compositional shifts in humans. This preliminary study aimed to describe the fecal bacterial community composition of people from Côte d’Ivoire harboring Giardia duodenalis, Entamoeba spp., and Blastocystis hominis, in trying to discover possible alterations in their fecal microbiota structure related to the presence of such parasites. Methodology: Twenty fecal samples were collected from people inhabiting three different localities of Côte d’Ivoire for copromicroscopic analysis and molecular identification of G. duodenalis, Entamoeba spp., and B. hominis. Temporal temperature gradient gel electrophoresis (TTGE) was used to obtain a fingerprint of the overall bacterial community; quantitative polymerase chain reaction (qPCR) was used to define the relative abundances of selected bacterial species/group, and multivariate statistical analyses were employed to correlate all data. Results: Cluster analysis revealed a significant separation of TTGE profiles into four clusters (p < 0.0001), with a marked difference for G. duodenalis-positive samples in relation to the others (p = 5.4×10-6). Interestingly, qPCR data showed how G. duodenalis-positive samples were related to a dysbiotic condition that favors potentially harmful species (such as Escherichia coli), while Entamoeba spp./B. hominis-positive subjects were linked to a eubiotic condition, as shown by a significantly higher Faecalibacterium prausnitzii-Escherichia coli ratio. Conclusions: This preliminary investigation demonstrates a differential fecal microbiota structure in subjects infected with G. duodenalis or Entamoeba spp./B. hominis, paving the way for using further next-generation DNA technologies to better understand host-parasite-bacteria interactions, aimed at identifying potential indicators of microbiota changes.