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Littérature scientifique sur le sujet « Phage interactions »

Auteur : Grafiati

Publié le 25 janvier 2025

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Articles de revues sur le sujet "Phage interactions"

Stone, Edel, Katrina Campbell, Irene Grant et Olivia McAuliffe. « Understanding and Exploiting Phage–Host Interactions ». Viruses 11, n^o 6 (18 juin 2019) : 567. http://dx.doi.org/10.3390/v11060567.

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Initially described a century ago by William Twort and Felix d’Herelle, bacteriophages are bacterial viruses found ubiquitously in nature, located wherever their host cells are present. Translated literally, bacteriophage (phage) means ‘bacteria eater’. Phages interact and infect specific bacteria while not affecting other bacteria or cell lines of other organisms. Due to the specificity of these phage–host interactions, the relationship between phages and their host cells has been the topic of much research. The advances in phage biology research have led to the exploitation of these phage–host interactions and the application of phages in the agricultural and food industry. Phages may provide an alternative to the use of antibiotics, as it is well known that the emergence of antibiotic-resistant bacterial infections has become an epidemic in clinical settings. In agriculture, pre-harvest and/or post-harvest application of phages to crops may prevent the colonisation of bacteria that are detrimental to plant or human health. In addition, the abundance of data generated from genome sequencing has allowed the development of phage-derived bacterial detection systems of foodborne pathogens. This review aims to outline the specific interactions between phages and their host and how these interactions may be exploited and applied in the food industry.

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Sacher, Jessica C., Muhammad Afzal Javed, Clay S. Crippen, James Butcher, Annika Flint, Alain Stintzi et Christine M. Szymanski. « Reduced Infection Efficiency of Phage NCTC 12673 on Non-Motile Campylobacter jejuni Strains Is Related to Oxidative Stress ». Viruses 13, n^o 10 (29 septembre 2021) : 1955. http://dx.doi.org/10.3390/v13101955.

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Campylobacter jejuni is a Gram-negative foodborne pathogen that causes diarrheal disease and is associated with severe post-infectious sequelae. Bacteriophages (phages) are a possible means of reducing Campylobacter colonization in poultry to prevent downstream human infections. However, the factors influencing phage-host interactions must be better understood before this strategy can be predictably employed. Most studies have focused on Campylobacter phage binding to the host surface, with all phages classified as either capsule- or flagella-specific. Here we describe the characterization of a C. jejuni phage that requires functional flagellar glycosylation and motor genes for infection, without needing the flagella for adsorption to the cell surface. Through phage infectivity studies of targeted C. jejuni mutants, transcriptomic analysis of phage-resistant mutants, and genotypic and phenotypic analysis of a spontaneous phage variant capable of simultaneously overcoming flagellar gene dependence and sensitivity to oxidative stress, we have uncovered a link between oxidative stress, flagellar motility, and phage infectivity. Taken together, our results underscore the importance of understanding phage-host interactions beyond the cell surface and point to host oxidative stress state as an important and underappreciated consideration for future phage-host interaction studies.

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Blasche, Sonja, Stefan Wuchty, Seesandra V. Rajagopala et Peter Uetz. « The Protein Interaction Network of Bacteriophage Lambda with Its Host, Escherichia coli ». Journal of Virology 87, n^o 23 (18 septembre 2013) : 12745–55. http://dx.doi.org/10.1128/jvi.02495-13.

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Although most of the 73 open reading frames (ORFs) in bacteriophage λ have been investigated intensively, the function of many genes in host-phage interactions remains poorly understood. Using yeast two-hybrid screens of all lambda ORFs for interactions with its hostEscherichia coli, we determined a raw data set of 631 host-phage interactions resulting in a set of 62 high-confidence interactions after multiple rounds of retesting. These links suggest novel regulatory interactions between theE. colitranscriptional network and lambda proteins. Targeted host proteins and genes required for lambda infection are enriched among highly connected proteins, suggesting that bacteriophages resemble interaction patterns of human viruses. Lambda tail proteins interact with both bacterial fimbrial proteins andE. coliproteins homologous to other phage proteins. Lambda appears to dramatically differ from other phages, such as T7, because of its unusually large number of modified and processed proteins, which reduces the number of host-virus interactions detectable by yeast two-hybrid screens.

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Zhang, Mingyue, Yanan Zhou, Xinyuan Cui et Lifeng Zhu. « The Potential of Co-Evolution and Interactions of Gut Bacteria–Phages in Bamboo-Eating Pandas : Insights from Dietary Preference-Based Metagenomic Analysis ». Microorganisms 12, n^o 4 (31 mars 2024) : 713. http://dx.doi.org/10.3390/microorganisms12040713.

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Bacteria and phages are two of the most abundant biological entities in the gut microbiome, and diet and host phylogeny are two of the most critical factors influencing the gut microbiome. A stable gut bacterial community plays a pivotal role in the host’s physiological development and immune health. A phage is a virus that directly infects bacteria, and phages’ close associations and interactions with bacteria are essential for maintaining the stability of the gut bacterial community and the entire microbial ecosystem. Here, we utilized 99 published metagenomic datasets from 38 mammalian species to investigate the relationship (diversity and composition) and potential interactions between gut bacterial and phage communities and the impact of diet and phylogeny on these communities. Our results highlight the co-evolutionary potential of bacterial–phage interactions within the mammalian gut. We observed a higher alpha diversity in gut bacteria than in phages and identified positive correlations between bacterial and phage compositions. Furthermore, our study revealed the significant influence of diet and phylogeny on mammalian gut bacterial and phage communities. We discovered that the impact of dietary factors on these communities was more pronounced than that of phylogenetic factors at the order level. In contrast, phylogenetic characteristics had a more substantial influence at the family level. The similar omnivorous dietary preference and closer phylogenetic relationship (family Ursidae) may contribute to the similarity of gut bacterial and phage communities between captive giant panda populations (GPCD and GPYA) and omnivorous animals (OC; including Sun bear, brown bear, and Asian black bear). This study employed co-occurrence microbial network analysis to reveal the potential interaction patterns between bacteria and phages. Compared to other mammalian groups (carnivores, herbivores, and omnivores), the gut bacterial and phage communities of bamboo-eating species (giant pandas and red pandas) exhibited a higher level of interaction. Additionally, keystone species and modular analysis showed the potential role of phages in driving and maintaining the interaction patterns between bacteria and phages in captive giant pandas. In sum, gaining a comprehensive understanding of the interaction between the gut microbiota and phages in mammals is of great significance, which is of great value in promoting healthy and sustainable mammals and may provide valuable insights into the conservation of wildlife populations, especially endangered animal species.

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Kaźmierczak, Zuzanna, Joanna Majewska, Magdalena Milczarek, Barbara Owczarek et Krystyna Dąbrowska. « Circulation of Fluorescently Labelled Phage in a Murine Model ». Viruses 13, n^o 2 (14 février 2021) : 297. http://dx.doi.org/10.3390/v13020297.

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Interactions between bacteriophages and mammals strongly affect possible applications of bacteriophages. This has created a need for tools that facilitate studies of phage circulation and deposition in tissues. Here, we propose red fluorescent protein (RFP)-labelled E. coli lytic phages as a new tool for the investigation of phage interactions with cells and tissues. The interaction of RFP-labelled phages with living eukaryotic cells (macrophages) was visualized after 20 min of co-incubation. RFP-labeled phages were applied in a murine model of phage circulation in vivo. Phages administered by three different routes (intravenously, orally, rectally) were detected through the course of time. The intravenous route of administration was the most efficient for phage delivery to multiple body compartments: 20 min after administration, virions were detected in lymph nodes, lungs, and liver; 30 min after administration, they were detectable in muscles; and 1 h after administration, phages were detected in spleen and lymph nodes. Oral and rectal administration of RFP-labelled phages allowed for their detection in the gastrointestinal (GI) tract only.

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Dicks, Leon M. T., et Wian Vermeulen. « Bacteriophage–Host Interactions and the Therapeutic Potential of Bacteriophages ». Viruses 16, n^o 3 (20 mars 2024) : 478. http://dx.doi.org/10.3390/v16030478.

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Healthcare faces a major problem with the increased emergence of antimicrobial resistance due to over-prescribing antibiotics. Bacteriophages may provide a solution to the treatment of bacterial infections given their specificity. Enzymes such as endolysins, exolysins, endopeptidases, endosialidases, and depolymerases produced by phages interact with bacterial surfaces, cell wall components, and exopolysaccharides, and may even destroy biofilms. Enzymatic cleavage of the host cell envelope components exposes specific receptors required for phage adhesion. Gram-positive bacteria are susceptible to phage infiltration through their peptidoglycan, cell wall teichoic acid (WTA), lipoteichoic acids (LTAs), and flagella. In Gram-negative bacteria, lipopolysaccharides (LPSs), pili, and capsules serve as targets. Defense mechanisms used by bacteria differ and include physical barriers (e.g., capsules) or endogenous mechanisms such as clustered regularly interspaced palindromic repeat (CRISPR)-associated protein (Cas) systems. Phage proteins stimulate immune responses against specific pathogens and improve antibiotic susceptibility. This review discusses the attachment of phages to bacterial cells, the penetration of bacterial cells, the use of phages in the treatment of bacterial infections, and the limitations of phage therapy. The therapeutic potential of phage-derived proteins and the impact that genomically engineered phages may have in the treatment of infections are summarized.

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Dunne, Matthew, Mario Hupfeld, Jochen Klumpp et Martin Loessner. « Molecular Basis of Bacterial Host Interactions by Gram-Positive Targeting Bacteriophages ». Viruses 10, n^o 8 (28 juillet 2018) : 397. http://dx.doi.org/10.3390/v10080397.

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The inherent ability of bacteriophages (phages) to infect specific bacterial hosts makes them ideal candidates to develop into antimicrobial agents for pathogen-specific remediation in food processing, biotechnology, and medicine (e.g., phage therapy). Conversely, phage contaminations of fermentation processes are a major concern to dairy and bioprocessing industries. The first stage of any successful phage infection is adsorption to a bacterial host cell, mediated by receptor-binding proteins (RBPs). As the first point of contact, the binding specificity of phage RBPs is the primary determinant of bacterial host range, and thus defines the remediative potential of a phage for a given bacterium. Co-evolution of RBPs and their bacterial receptors has forced endless adaptation cycles of phage-host interactions, which in turn has created a diverse array of phage adsorption mechanisms utilizing an assortment of RBPs. Over the last decade, these intricate mechanisms have been studied intensely using electron microscopy and X-ray crystallography, providing atomic-level details of this fundamental stage in the phage infection cycle. This review summarizes current knowledge surrounding the molecular basis of host interaction for various socioeconomically important Gram-positive targeting phage RBPs to their protein- and saccharide-based receptors. Special attention is paid to the abundant and best-characterized Siphoviridae family of tailed phages. Unravelling these complex phage-host dynamics is essential to harness the full potential of phage-based technologies, or for generating novel strategies to combat industrial phage contaminations.

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Tan, Demeng, Lone Gram et Mathias Middelboe. « Vibriophages and Their Interactions with the Fish Pathogen Vibrio anguillarum ». Applied and Environmental Microbiology 80, n^o 10 (7 mars 2014) : 3128–40. http://dx.doi.org/10.1128/aem.03544-13.

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ABSTRACTVibrio anguillarumis an important pathogen in aquaculture, responsible for the disease vibriosis in many fish and invertebrate species. Disease control by antibiotics is a concern due to potential development and spread of antibiotic resistance. The use of bacteriophages to control the pathogen may offer a non-antibiotic-based approach to reduce vibriosis. A detailed understanding of the phage-host interaction is needed to evaluate the potential of phages to control the pathogen. In this study, we examined the diversity and interactions of 11 vibriophages, 24V. anguillarumstrains, and 13Vibriospecies strains. Together, the host ranges of the 11 phages covered all of the tested 37Vibriosp. host strains, which represented considerable temporal (20 years) and geographical (9 countries) differences in their origins of isolation. Thus, despite the occurrence of unique susceptibility patterns of the individual host isolates, key phenotypic properties related to phage susceptibility are distributed worldwide and maintained in the globalVibriocommunity for decades. The phage susceptibility pattern of the isolates did not show any relation to the physiological relationships obtained from Biolog GN2 profiles, demonstrating that similar phage susceptibility patterns occur across broad phylogenetic and physiological differences inVibriostrains. Subsequent culture experiments with two phages and twoV. anguillarumhosts demonstrated an initial strong lytic potential of the phages. However, rapid regrowth of both phage-resistant and phage-sensitive cells following the initial lysis suggested that several mechanisms of protection against phage infection had developed in the host populations.

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Deveau, Hélène, Marie-Rose Van Calsteren et Sylvain Moineau. « Effect of Exopolysaccharides on Phage-Host Interactions in Lactococcus lactis ». Applied and Environmental Microbiology 68, n^o 9 (septembre 2002) : 4364–69. http://dx.doi.org/10.1128/aem.68.9.4364-4369.2002.

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ABSTRACT In this study, we report that Lactococcus lactis strains producing exopolysaccharides (EPS) are sensitive to virulent phages. Eight distinct lytic phages (Q61 to Q68) specifically infecting Eps+ strains were isolated in 47 buttermilk samples obtained from 13 North American factories. The eight phages were classified within the 936 species by the multiplex PCR method, indicating that these phages are not fundamentally distinct from those infecting Eps− L. lactis strains. The host range of these phages was determined with 19 Lactococcus strains, including 7 Eps+ and 12 Eps− cultures. Three phages (Q62, Q63, and Q64) attacked only the Eps+ strain SMQ-419, whereas the five other phages (Q61, Q65, Q66, Q67, and Q68) infected only the Eps+ strain SMQ-420. The five other Eps+ strains (H414, MLT2, MLT3, SMQ-461, and SMQ-575) as well as the 12 Eps− strains were insensitive to these phages. The monosaccharide composition of the polymer produced by the seven Eps+ strains was determined. The EPS produced by strains MLT3, SMQ-419, and SMQ-575 contained glucose, galactose, and rhamnose. The EPS fabricated by H414 contained only galactose. The EPS made by MLT2, SMQ-420, and SMQ-461 contained glucose and galactose. These findings indicate that the sugar composition of the EPS has no effect on phage sensitivity. The plasmid encoding the eps operon was cured from the two phage-sensitive strains. The cured derivatives were still phage sensitive, which indicates that EPS are not necessary for phage infection. Phage adsorption assays showed that the production of EPS does not confer a significant phage resistance phenotype.

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Loessner, Holger, Insea Schlattmeier, Marie Anders-Maurer, Isabelle Bekeredjian-Ding, Christine Rohde, Johannes Wittmann, Cornelia Pokalyuk, Oleg Krut et Christel Kamp. « Kinetic Fingerprinting Links Bacteria-Phage Interactions with Emergent Dynamics : Rapid Depletion of Klebsiella pneumoniae Indicates Phage Synergy ». Antibiotics 9, n^o 7 (14 juillet 2020) : 408. http://dx.doi.org/10.3390/antibiotics9070408.

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The specific temporal evolution of bacterial and phage population sizes, in particular bacterial depletion and the emergence of a resistant bacterial population, can be seen as a kinetic fingerprint that depends on the manifold interactions of the specific phage–host pair during the course of infection. We have elaborated such a kinetic fingerprint for a human urinary tract Klebsiella pneumoniae isolate and its phage vB_KpnP_Lessing by a modeling approach based on data from in vitro co-culture. We found a faster depletion of the initially sensitive bacterial population than expected from simple mass action kinetics. A possible explanation for the rapid decline of the bacterial population is a synergistic interaction of phages which can be a favorable feature for phage therapies. In addition to this interaction characteristic, analysis of the kinetic fingerprint of this bacteria and phage combination revealed several relevant aspects of their population dynamics: A reduction of the bacterial concentration can be achieved only at high multiplicity of infection whereas bacterial extinction is hardly accomplished. Furthermore the binding affinity of the phage to bacteria is identified as one of the most crucial parameters for the reduction of the bacterial population size. Thus, kinetic fingerprinting can be used to infer phage–host interactions and to explore emergent dynamics which facilitates a rational design of phage therapies.

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Thèses sur le sujet "Phage interactions"

Ouennane, Siham. « Interactions phage-hôte chez Streptococcus pneumoniae ». Doctoral thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27790.

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Streptococcus pneumoniae est une bactérie à la fois commensale et pathogène opportuniste chez l’humain. Elle est responsable de nombreuses infections telles que la pneumonie, la méningite, l’otite moyenne et la sinusite. En maladie infectieuse, S. pneumoniae occupe une place importante en tant que l’une des principales causes de morbidité et de mortalité dans le monde. Elle est dotée de plusieurs capacités fascinantes, comme la compétence naturelle pour l’aider à résister aux antibiotiques et la grande diversité des sérotypes capsulaires pour contourner la vaccination. Puisque la résistance aux antibiotiques ne cesse de menacer l’efficacité des thérapies standards, la thérapie par phage est maintenant reconsidérée comme une des alternatives thérapeutiques. La réévaluation des phages fait renaitre l’espoir thérapeutique, mais sans élucider leur mécanisme d’interaction et décortiquer leur mystère cet espoir restera modeste. Ce projet de doctorat consiste à mieux comprendre les phages infectant S. pneumoniae et les interactions phage-hôte. Dans un premier temps, le potentiel des pneumophages à infecter Streptococcus mitis, une espèce phylogénétiquement proche de S. pneumoniae, a été mis en évidence. Deux pneumophages se sont avérés les premiers phages virulents capables d’infecter S. mitis, bactérie pathogène responsable d’endocardite. Les deux phages pouvaient non seulement se répliquer dans S. mitis mais également produisent des plages de lyses plus visibles. Ensuite, la comparaison du génome des phages a confirmé que le changement de l’hôte n’induit aucune variation aux génomes des phages testés. Cependant, plusieurs mutations ont été observées dans la séquence génomique du podophage sauvage et il a fait ensuite l’objet d’une nouvelle annotation. Dans un deuxième temps, l’étude des interactions phage-hôte chez S. pneumoniae a été approfondie. Pour ce faire, l’implication de plusieurs facteurs de l’hôte dans la réplication des pneumophages a été étudiée. Plusieurs gènes pneumococciques se sont avérés nécessaires ou impliqués pour assurer l'efficacité de la réplication des phages seuls ou en cocktail. D’un autre côté, en étudiant ces facteurs de l’hôte, des gènes/ protéines potentiellement essentiels à la viabilité de S. pneumoniae ont été identifiés. Cette étude a aussi permis d’identifier de nouvelles cibles thérapeutiques et donne un nouvel aperçu du réseau complexe des interactions phage-hôte.
Streptococcus pneumoniae is a commensal and opportunistic pathogen bacterium, exclusively found in humans. It is the main agent of many infections such as pneumonia, meningitis, otitis media and sinusitis. S. pneumoniae infections are a major cause of morbidity and mortality worldwide. S. pneumoniae has several fascinating abilities, such as natural competence to facilitate the acquisition of antibiotic resistance genes and diversity of capsular serotypes to circumvent the vaccination. The rise of antibiotic resistant bacteria continues to threaten the effectiveness of standard therapies and as such phage therapy is now reconsidered as a therapeutic alternative. The reevaluation of phages as therapeutic agents must go through a better understanding of phage-bacterium interactions. This PhD thesis aims to better understand S. pneumoniae virulent phages and phage-host interactions. First, the ability of pneumophages to infect Streptococcus mitis, a species phylogenetically related to S. pneumoniae, was demonstrated. The pneumophages are the first two virulent phages able to infect this pathogenic bacterium, the common cause of bacterial endocarditis. Both pneumophages could not only replicate in S. mitis but also produced more visible plaques on this host. The comparison of the genomes of each phage grown on both hosts produced identical nucleotide sequences, confirming that S. mitis as a host does not induce any nucleotide variation. However, the genomic sequence of wild-type podophage was different than the previously reported sequence and it was the subject of a new annotation. In addition, S. pneumoniae phage-host interactions were investigated. The involvement of several host factors in replication of both pneumophages was observed. Indeed, several pneumococcal genes were found to be necessary or involved to ensure efficient phage replication. Moreover, the study of these host factors has led to the identification of new genes that appear to be essential for viability and normal growth of S. pneumoniae. This project led to identify new potential therapeutic targets and provided new insight into the complex network of phage-host interactions.

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Eccleston, Jacqueline Dawn. « Community richness and host-phage interactions in soil ». Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316817.

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Marcinkiewicz, Ashley. « Bacterial and phage interactions influencing Vibrio parahaemolyticus ecology ». Thesis, University of New Hampshire, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10127507.

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Vibrio parahaemolyticus, a human pathogenic bacterium, is a naturally occurring member of the microbiome of the Eastern oyster. As the nature of this symbiosis in unknown, the oyster presents the opportunity to investigate how microbial communities interact with a host as part of the ecology of an emergent pathogen of importance. To define how members of the oyster bacterial microbiome correlate with V. parahaemolyticus, I performed marker-based metagenetic sequencing analyses to identify and quantify the bacterial community in individual oysters after culturally-quantifying V. parahaemolyticus abundance. I concluded that despite shared environmental exposures, individual oysters from the same collection site varied both in microbiome community and V. parahaemolyticus abundance, and there may be an interaction with V. parahaemolyticus and Bacillus species. In addition, to elucidate the ecological origins of pathogenic New England ST36 populations, I performed whole genome sequencing and phylogenetic analyses. I concluded ST36 strains formed distinct subpopulations that correlated both with geographic region and unique phage content that can be used as a biomarker for more refined strain traceback. Furthermore, these subpopulations indicated there may have been multiple invasions of this non-native pathogen into the Atlantic coast.

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Yang, Joy Ph D. (Joy Yu)Massachusetts Institute of Technology. « Statistically inferring the mechanisms of phage-host interactions ». Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/123250.

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Thesis: Ph. D., Massachusetts Institute of Technology, Computational and Systems Biology Program, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 113-121).
Bacteriophage and their hosts are locked in an age-old arms race. Successful bacteria are subject to predation, forcing the population to diversify, and phage are also quick to adapt tactics for infecting these potential hosts. Sampling of closely related bacterial strains that differ in phage infection profiles can further elucidate the mechanisms of infection. The Polz Lab maintains the Nahant Collection - 243 Vibrio strains challenged by 241 unique phage, all with sequenced genomes. This is the largest phylogenetically resolved host-range cross test available to date. Genetically mapping out the depths of this dataset requires carefully designed analysis techniques as well as further experimental exploration. First, we narrow in on a specific phage in the Nahant Collection, 2.275.0, to characterize the pressures that may select for phage that shuttle their own translational machinery.
While translation is generally considered a hallmark of cellular life, some phage carry abundant tRNA. 2.275.0 carries 18 tRNA spanning 13 amino acids. We find that while encoding translation-related components requires shuttling a larger phage genome, it also reduces dependence on host translational machinery, allowing the phage to be more aggressive in degrading and recycling the host genome and other resources required for replication. Next we develop a systematic approach for uncovering genomic features that underlie phage-host interactions. We find that correcting for phylogenetic relationships allows us to pick out relevant signals that would otherwise be drowned out by spurious correlations resulting from statistically oversampled blooms of microbes. Using these results, we wrote an interative javascript visualization to facilitate the process of developing testable hypotheses concerning the mechanisms of phage infection and host response.
From the visualization, we are able to identify, in the hosts, mobile genetic elements containing restriction modification systems that may defend against infection, as well as membrane protein modifications that may serve as phage attachment sites.
by Joy Yang.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Computational and Systems Biology Program

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Samson, Julie. « Interactions phage-hôte et caractérisation de la résistance aux phages chez Lactococcus lactis ». Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30167/30167.pdf.

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Bactéries et phages sont en perpétuelle compétition dans l’environnement et évoluent conjointement. Plusieurs mécanismes ont été développés de part et d’autre pour maintenir un état d’équilibre. D’un côté, les phages sont des entités qui se répliquent efficacement et rapidement en parasitant leur bactérie hôte. D’un autre côté, les bactéries ont acquis des mécanismes de résistance aux bactériophages tels que les systèmes d’avortement de l’infection (Abi) pour limiter l’infection et la propagation des phages dans les populations bactériennes. Plus spécifiquement, le système antiphage AbiQ a été isolé de la bactérie Lactococcus lactis. Cette dernière est utilisée pour la production de divers produits laitiers fermentés. Malgré cet environnement contrôlé, des phages peuvent perturber les fermentations s’ils sont présents dans le lait et les usines. Il n’est donc pas surprenant que cette bactérie possède des systèmes contre ces envahisseurs. Le système antiphage AbiQ serait similaire à un mécanisme de type toxine-antitoxine (TA), mais son fonctionnement demeure jusqu’à maintenant inconnu. Au cours de ce projet de doctorat, trois objectifs ont été poursuivis afin de comprendre la relation entre la bactérie Lactococcus lactis et ses phages. Dans un premier temps, le génome du phage 949, un membre d’un groupe rare de lactophages portant son nom, a été séquencé et caractérisé. Une comparaison de tous les génomes de phages infectant L. lactis a été réalisée afin de confirmer la classification actuelle. Dans un deuxième temps, le mode d’action toxine-antitoxine du système AbiQ de L. lactis a été approfondi. Pour ce faire, des expériences ont été réalisées afin de démontrer que ce système est un mécanisme de type TA composé d’une antitoxine d’ARN et d’une toxine protéique avec une activitée ribonucléase. Dans un troisième temps, l’effet d’AbiQ sur la réplication des phages a été évalué. En isolant des phages mutants ayant la capacité de contourner le mécanisme, des cibles phagiques potentielles du système AbiQ ont été identifiées. Comprendre la relation phage-hôte est la clé pour le développement de bactéries résistantes aux phages dans un contexte de production industrielle ou pour limiter l’apparition de résistance aux phages lors du traitement des infections bactériennes par la thérapie phagique.
Bacteria and phages are continuously challenging each other and evolve in most ecosystems. Many strategies have been adapted by both of them to reach an equilibrium state. On one side, phages can infect efficiently and rapidly their bacterial host. On the other side, bacteria have acquired antiphage mechanisms to resist phage infection and limit their propagation such as abortive infection mechanisms (Abi). Specifically, the AbiQ antiphage system was isolated from Lactococcus lactis. This bacterium is used to produce an array of fermented dairy products. Even if this environment is tightly controlled, phages are ubiquitous in milk and in factories, and they can affect fermentations. The AbiQ antiphage system ressembles to a toxin-antitoxin (TA) system, but its mode of action is still unknown. In this study, three objectives were persued in order to better understand the relationship between Lactococcus lactis and its phages. First, the phage 949 genome, a member of a rare lactophage group that bears its name, was sequenced and characterized. A genome comparison of all lactococcal phages sequenced to date was done to confirm the current phage classification. In the second objective, we have confirmed that AbiQ is indeed a toxin-antitoxin system. Experiments were performed to demonstrate that this TA mechanism is composed of a RNA antitoxin and a protein toxin with ribonuclease activity. In the third objective, the effect of AbiQ on the phage replication was evaluated. By isolating phage mutants able to escape the mechanism, different phage targets were identified. Understanding the phage-host relationships is the key to develop efficient tools to reduce phage infection in industrial settings or to limit the development of phage resistance in other applications such as in phage therapy.

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Ramkissoon, Yashin Danjay. « Interaction cloning by phage display : protein interactions of the human testis determining factor, SRY ». Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627297.

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Bankier, Claire. « Coevolutionary interactions between bacteria and phage in natural environments ». Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44556.

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Bacteria and their viruses (bacteriophage, phage) are the most abundant and diverse taxonomic groups, but ecological and evolutionary research on bacteria-phage interactions has largely focused on studies of simplified communities using a few model organisms. The goal of the thesis is to understand how bacteria and phage interact within natural environments, and how these interactions impact the patterns of phage infectivity and bacterial resistance. Here I investigate the effects of natural environments on the coevolutionary patterns of bacteria (Pseudomonas fluorescens) and phage (SBW25Φ2). In chapter 3 I investigate the effects of nineteen different communities on the coevolutionary interactions of SBW25 and phage, and the degree to which the infectivity of phage to its host, SBW25, changes depending on their local microbial community. Chapter 4 aimed to understand the effects of varying diversities of communities on coevolutionary interactions. In Chapter 5, I looked at how coevolutionary interactions were affected by different communities in different abiotic conditions (pH, temperature and nutrient concentration) and the effect communities had on the ability of SBW25 to adapt to the abiotic conditions. Understanding how biological and physical factors affect coevolutionary interactions in natural environments allows predictions of how phage and bacteria coevolve in natural and unnatural settings.

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Räisänen, L. (Liisa). « Phage-host interactions in Lactobacillus delbrueckii : host recognition and transcription of early phage genes ». Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514284250.

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Abstract The scope of this study includes aspects of phage evolution and antagonistic/mutualistic coevolution between a phage and its host. As a basic study it may provide tools for developing phage resistant starters and offer regulatory elements and factors for biotechnological applications. The LL-H anti-receptor was characterized by isolation of spontaneous LL-H host range mutants and subsequent sequencing of candidate genes. All LL-H host range mutants carried a single point mutation at the 3' end of a minor tail protein encoding gene g71. The genomic location of g71 is congruent with the other verified anti-receptor genes found in the λ supergroup. The C-terminus of Gp71 determines the adsorption specificity of phage LL-H similarly for the number of phages infecting Gram-positive and Gram-negative bacteria. A Gp71 homolog of phage JCL1032 showed 62% identity to LL-H Gp71 within the last 300 amino acids at the C-terminus. Lactobacillus delbrueckii phage receptors were investigated by the purification of different cell surface structures. Certain Lb. delbrueckii phages from homology groups a and c including LL-H, LL-H host range mutants and JCL1032, were specifically inactivated by the LTAs. In structural analyses LTAs showed differences in the degree of α-glucosyl and ᴅ-alanyl substitution. α-glucose is necessary for LL-H adsorption. A high level of ᴅ-alanine esters in LTA backbones inhibited Lb. delbrueckii phage inactivation in general. Lysogenization of strain ATCC 15808 with the temperate phage JCL1032 revealed a rarely described coexistence of phage adsorption resistance and phage immunity, which could not be explained by lysogenic conversion. In this case the role of spontaneously induced JCL1032 may be significant. The LL-H early gene region was localized between the dysfunctional lysogeny module and the terminase encoding genes. The function of five ORFs could be connected to phage DNA replication and/or homologous recombination. Transcription of LL-H genes could be divided into two, possibly three, phases in which large gene clusters were sequentially transcribed. The intensity of the late transcripts exceeded the intensity of the early transcripts by several times. Two candidate genes for transcription regulators were found. One of the two candidates is the first ORF in the LL-H early gene region.

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Gonzalez, Floricel. « Investigation of flagellotropic phage interactions with their motile host bacteria ». Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103940.

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Bacteriophages cohabit with their bacterial hosts and shape microbial communities. To initiate infection, phages use bacterial components as receptors to recognize and attach to hosts. Flagellotropic phages utilize bacterial flagella as receptors. Studies focused on uncovering mechanistic details of flagellotropic phage infection are lacking. As the number of phage-based applications grows, it is important to understand these details to predict the potential outcomes of phage therapy. To this end, we studied two flagellotropic phages: Agrobacterium phage 7-7-1 and bacteriophage χ. Phage 7-7-1 infects Agrobacterium spp., while bacteriophage χ infects Salmonella and Escherichia coli. Chapter 1 consists of a literature review. Chapter 2 addresses factors underlying phage-bacteria coexistence. We document the emergence of a sector-shaped lysis pattern following co-inoculation of phage χ and one of its Salmonella hosts on swim plates. We propose that this pattern serves as a reporter for balanced phage-bacteria coexistence. Using a combined experimental and mathematical modelling approach, we discovered that variations to intrinsic factors (i.e., bacterial motility, phage adsorption) skews the pattern towards either bacterial or phage predominance. Thus, this computational model may be used to predict phage therapy application outcomes. Chapter 3 details the identification of cell surface receptors essential for phage 7-7-1 infection using a transposon mutagenesis approach. We identified three Agrobacterium sp. H13-3 genes involved in phage 7-7-1 infection. Using mass spectrometry and other analyses, we determined that the LPS profiles of strains lacking these genes varied compared to the wild type. Thus, LPS is a secondary cell surface receptor for phage 7-7-1. Chapter 4 focuses on the discovery of phage encoded receptor binding proteins (RBPs) in Agrobacterium phage 7-7-1. Using an RBP screen, we discovered three candidate RBPs. We learned that our top candidate, Gp4, inhibits the growth of Agrobacterium sp. H13-3 cells in a motility and glycan dependent manner. Because of its bacteriostatic activities, this protein is a promising candidate for therapeutic use. Overall, the described works contribute to a deepened understanding of flagellotropic phage infection and the factors influencing their coexistence with motile bacteria. These works will contribute towards the development of phage therapies using whole phage or their components.
Doctor of Philosophy
Bacteriophages, or phages for short, are the natural killers of bacteria. Like antibiotics, they can also be used as medicines to treat bacterial infections. Their attack on bacteria begins by recognizing specific parts of the bacterial cell and attaching to them. These parts are called receptors. To use phages as medicines it is important to understand how they recognize and kill bacteria. This information is helpful when deciding which phage should be given to treat a bacterial infection and to predict the outcomes of these treatments. In this work, we focused on two phages to answer different questions. Both phages use long helical thread-like structures, called flagella, as receptors. Flagella help the bacteria to move through the environment and reach new areas with more nutrients. One of these flagella-dependent phages, called phage 7-7-1, infects plant pathogens that cause tumor-like growth in plants. We found that this phage uses two very different host cell components during infection and identified one of the phage proteins that interacts with these receptors. This protein prevents the growth of the plant pathogen, which makes it a promising candidate for therapeutic use. We also investigated how another bacterial virus, bacteriophage χ, is spread throughout the environment and co-exists with its motile bacterial host. We built a computational model that can predict how altering different variables affects phage-bacteria coexistence. With additional research, this model will be a useful tool for predicting the outcomes following phage treatment.

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Fan, Yan Baranger Anne M. Katzenellenbogen John A. Zhao Huimin Silverman Scott K. « Exploring protein-RNA interactions with site-directed mutagenesis and phage display ». Urbana, IL. : University of Illinois, 2009. http://hdl.handle.net/2142/14755.

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Livres sur le sujet "Phage interactions"

Peter, Marsh. Interactions between actinophage and streptomycetes in soil and the fate of phage-borne genes. [s.l.] : typescript, 1993.

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StephenA, Paipetis, Papanicolaou G. C. 1943- et COMP '88, dir. Phase interaction in composite materials. Wallingford : Omega Scientific, 1992.

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Aboul-Kassim, T. A. T., et B. R. T. Simoneit, dir. Pollutant-Solid Phase Interactions Mechanisms, Chemistry and Modeling. Berlin/Heidelberg : Springer-Verlag, 2001. http://dx.doi.org/10.1007/10638318.

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Anne-Christine, Davis, Brandenberger Robert Hans, North Atlantic Treaty Organization. Scientific Affairs Division. et NATO Advanced Study Institute on Formation and Interactions of Topological Defects (1994 : Cambridge, England), dir. Formation and interactions of topological defects. New York : Plenum Press, 1995.

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Cleymans, Jean, dir. Phase Structure of Strongly Interacting Matter. Berlin, Heidelberg : Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-87821-3.

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Boronenkov, Vladislav, Michael Zinigrad, Leopold Leontiev, Edward Pastukhov, Mikhail Shalimov et Sergey Shanchurov. Phase Interaction in the Metal - Oxide Melts - Gas -System. Berlin, Heidelberg : Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-22377-8.

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M, Nikjooy, et United States. National Aeronautics and Space Administration., dir. Flow interaction experiment aerothermal modeling, phase II : Final report. [Washington, DC] : National Aeronautics and Space Administration, 1993.

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Dobrushin, R. L. Wulff construction : A global shape from local interaction. Providence, R.I : American Mathematical Society, 1992.

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Savit͡skiĭ, A. P. Liquid phase sintering of the systems with interacting components. Tomsk : [s.n.], 1993.

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Papanicolaou, G. C. Hydrodynamic Behavior and Interacting Particle Systems. New York, NY : Springer US, 1987.

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Chapitres de livres sur le sujet "Phage interactions"

Trinh, Jimmy T., et Lanying Zeng. « Phage-Phage Interactions ». Dans Biocommunication of Phages, 87–102. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45885-0_4.

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Taylor, Milton W. « Phage Therapy and the Future ». Dans Viruses and Man : A History of Interactions, 309–19. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-07758-1_16.

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Abedon, Stephen T. « Phage Therapy : Various Perspectives on How to Improve the Art ». Dans Host-Pathogen Interactions, 113–27. New York, NY : Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-7604-1_11.

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Segvich, Sharon, et David H. Kohn. « Phage Display as a Strategy for Designing Organic/Inorganic Biomaterials ». Dans Biological Interactions on Materials Surfaces, 115–32. New York, NY : Springer US, 2009. http://dx.doi.org/10.1007/978-0-387-98161-1_6.

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Selvaraj, Chandrabose, et Sanjeev Kumar Singh. « Phage Protein Interactions in the Inhibition Mechanism of Bacterial Cell ». Dans Biocommunication of Phages, 121–42. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45885-0_6.

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Lüchow, Susanne, Gustav N. Sundell et Ylva Ivarsson. « Identification of PDZ Interactions by Proteomic Peptide Phage Display ». Dans Methods in Molecular Biology, 41–60. New York, NY : Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1166-1_3.

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Svircev, Antonet M., Susan M. Lehman, Peter Sholberg, Dwayne Roach et Alan J. Castle. « Phage Biopesticides and Soil Bacteria : Multilayered and Complex Interactions ». Dans Soil Biology, 215–35. Berlin, Heidelberg : Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14512-4_8.

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Dantas, Rodolfo, Marcelo Brocchi et Taícia Pacheco Fill. « Chemical-Biology and Metabolomics Studies in Phage-Host Interactions ». Dans Advances in Experimental Medicine and Biology, 71–100. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-41741-2_4.

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Hertveldt, Kirsten, Tim Beliën et Guido Volckaert. « General M13 Phage Display : M13 Phage Display in Identification and Characterization of Protein–Protein Interactions ». Dans Methods in Molecular Biology, 321–39. Totowa, NJ : Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60327-565-1_19.

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Liang, Xiaolong, et Mark Radosevich. « Phage Communication and the Ecological Implications on Microbial Interactions, Diversity, and Function ». Dans Biocommunication of Phages, 71–86. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45885-0_3.

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Actes de conférences sur le sujet "Phage interactions"

Chen, Yifei, Weizhong Zhao, Xinhui Tu et Tingting He. « An Improved Prediction Model for Phage-host Interactions Based on Fusing Global and Local Semantics of RBP Information ». Dans 2024 IEEE International Conference on Bioinformatics and Biomedicine (BIBM), 1449–52. IEEE, 2024. https://doi.org/10.1109/bibm62325.2024.10821906.

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Xiao, Da-Wu, Chong Chen et Ren-Bao Liu. « Spontaneously Squeezing Superradiant Laser ». Dans CLEO : Fundamental Science, FW4J.7. Washington, D.C. : Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_fs.2024.fw4j.7.

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We investigate a superradiant lasing system with atom-atom interaction. We find that this interaction induces a squeezed lasing phase, demonstrating the importance of coherent many-body interactions in lasing.

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Gao, Chengkuan, Prabhav Gaur, Shimon Rubin et Yeshaiahu Fainman. « Self-Induced Optical Nonlinear-Nonlocal Effect and Short-Term Memory for Chip-Scale Reservoir Computing ». Dans CLEO : Science and Innovations, SF2M.3. Washington, D.C. : Optica Publishing Group, 2024. http://dx.doi.org/10.1364/cleo_si.2024.sf2m.3.

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We demonstrate nonlinear and nonlocal optical phase change effects due to thermocapillary deformation of thin liquid film interacting with photonic mode in silicon photonic waveguide. The interaction allows storing information in the liquid film, achieving short term memory, and implementing compact chip-scale Reservoir Computing (RC)

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Tao, Pengyan, Chien-Hung Yeh, Weifeng Li, Kaiwen Xu et Wenbin Shi. « Exploring Cardiopulmonary Interactions : A Novel Phase-Amplitude Coupling Method ». Dans 2024 46th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 1–5. IEEE, 2024. https://doi.org/10.1109/embc53108.2024.10782259.

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Lopez, Juan Fernando, Jesus Alfonso Lopez Sotelo, Diogo Leite et Carlos Pena-Reyes. « Applying one-class learning algorithms to predict phage-bacteria interactions ». Dans 2019 IEEE Latin American Conference on Computational Intelligence (LA-CCI). IEEE, 2019. http://dx.doi.org/10.1109/la-cci47412.2019.9037032.

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Ataee, Shabnam, Oscar Rodriguez, Xavier Brochet et Carlos Andres Pena. « Towards BacterioPhage Genetic Edition : Deep Learning Prediction of Phage-Bacterium Interactions ». Dans 2020 IEEE International Conference on Bioinformatics and Biomedicine (BIBM). IEEE, 2020. http://dx.doi.org/10.1109/bibm49941.2020.9313487.

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Andrews, Simeon, et Joel Malek. « High-Throughput Discovery of Cancer Cell Surface Interactions by Pairing cDNA Phage Display and Next Generation Sequencing ». Dans Qatar Foundation Annual Research Conference Proceedings. Hamad bin Khalifa University Press (HBKU Press), 2016. http://dx.doi.org/10.5339/qfarc.2016.hbpp1636.

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Zhu, Richard, et Sujata Bhatia. « Optimizing COVID-19 Vaccine Diffusion in Respiratory Mucosa through Stokes-Einstein Modeling ». Dans 2022 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/dmd2022-1065.

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Abstract SARS-COV-2 vaccines, all of which are currently intramuscular shots, have the ability to prevent serious injury. However, the absence of sufficient mucosal immunity is a major concern. To counteract this deficiency that has led to continued transmission from vaccinated individuals and breakthrough cases, reformulating vaccines to be inhalable presents a logical administration route. Predecessor research has reported the inhalable route to be viable as aerosolized vaccine nanoparticles, AAV phage nanoparticles, and PIV-5 viruses were recently identified to elicit immune responses. In this study, the diffusion of vaccine nanoparticles across the mucosa is characterized and modeled, with respect to their observed behavior from previous studies in relation to the Stokes-Einstein equation, to predict the most efficient model of an inhalable COVID-19 vaccine. The Stokes-Einstein equation has been used in several studies to predict diffusion coefficients. These predictions may be modified to fit the specifications of mucosal interactions. It was determined that mucosal interactions play a significant role in vaccine nanoparticle diffusion, as demonstrated by the viral vector and virus-like nanoparticle diffusion, and can be characterized by an equivalent hydrodynamic radius. Moreover, as a counter to mucosal interactions, PEGylation was found to drastically decrease the viscous slowing of the mucus medium.

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Goswami, Neha, et Gabriel Popescu. « Imaging E. coli – bacteriophage interaction using spatial light interference microscopy (SLIM) ». Dans Quantitative Phase Imaging VII, sous la direction de Gabriel Popescu, YongKeun Park et Yang Liu. SPIE, 2021. http://dx.doi.org/10.1117/12.2584448.

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Guizard, Stéphane. « Laser dielectric interactions : new insight from double-pulse experiments ». Dans Advances in Ultrafast Condensed Phase Physics III, sous la direction de Vladislav Yakovlev et Stefan Haacke. SPIE, 2022. http://dx.doi.org/10.1117/12.2624512.

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Rapports d'organisations sur le sujet "Phage interactions"

Gurevitz, Michael, Michael E. Adams, Boaz Shaanan, Oren Froy, Dalia Gordon, Daewoo Lee et Yong Zhao. Interacting Domains of Anti-Insect Scorpion Toxins and their Sodium Channel Binding Sites : Structure, Cooperative Interactions with Agrochemicals, and Application. United States Department of Agriculture, décembre 2001. http://dx.doi.org/10.32747/2001.7585190.bard.

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Integrated pest management in modern crop protection may combine chemical and biological insecticides, particularly due to the risks to the environment and livestock arising from the massive use of non-selective chemicals. Thus, there is a need for safer alternatives, which target insects more specifically. Scorpions produce anti-insect selective polypeptide toxins that are biodegradable and non-toxic to warm-blooded animals. Therefore, integration of these substances into insect pest control strategies is of major importance. Moreover, clarification of the molecular basis of this selectivity may provide valuable information pertinent to their receptor sites and to the future design of peptidomimetic anti-insect specific substances. These toxins may also be important for reducing the current overuse of chemical insecticides if they produce a synergistic effect with conventional pesticides. Based on these considerations, our major objectives were: 1) To elucidate the three-dimensional structure and toxic-site of scorpion excitatory, "depressant, and anti-insect alpha toxins. 2) To obtain an initial view to the sodium channel recognition sites of the above toxins by generating peptide decoys through a phage display system. 3) To investigate the synergism between toxins and chemical insecticides. Our approach was to develop a suitable expression system for toxin production in a recombinant form and for elucidation of toxin bioactive sites via mutagenesis. In parallel, the mode of action and synergistic effects of scorpion insecticidal toxins with pyrethroids were studied at the sodium channel level using electrophysiological methods. Objective 1 was achieved for the alpha toxin, LqhaIT Zilberberg et al., 1996, 1997; Tugarinov et al., 1997; Froy et al., 2002), and the excitatory toxin, Bj-xtrIT (Oren et al., 1998; Froy et al., 1999; unpublished data). The bioactive surface of the depressant toxin, LqhIT2, has been clarified and a crystal of the toxin is now being analyzed (unpublished). Objective 2 was not successful thus far as no phages that recognize the toxins were obtained. We therefore initiated recently an alternative approach, which is introduction of mutations into recombinant channels and creation of channel chimeras. Objective 3 was undertaken at Riverside and the results demonstrated synergism between LqhaIT or AaIT and pyrethroids (Lee et al., 2002). Furthermore, negative cross-resistance between pyrethroids and scorpion toxins (LqhaIT and AaIT) was demonstrated at the molecular level. Although our study did not yield a product, it paves the way for future design of selective pesticides by capitalizing on the natural competence of scorpion toxins to distinguish between sodium channels of insects and vertebrates. We also show that future application of anti-insect toxins may enable to decrease the amounts of chemical pesticides due to their synergism.

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Eyal, Yoram, et Sheila McCormick. Molecular Mechanisms of Pollen-Pistil Interactions in Interspecific Crossing Barriers in the Tomato Family. United States Department of Agriculture, mai 2000. http://dx.doi.org/10.32747/2000.7573076.bard.

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During the evolutionary process of speciation in plants, naturally occurring barriers to reproduction have developed that affect the transfer of genes within and between related species. These barriers can occur at several different levels beginning with pollination-barriers and ending with hybrid-breakdown. The interaction between pollen and pistils presents one of the major barriers to intra- and inter-specific crosses and is the focus of this research project. Our long-term goal in this research proposal was defined to resolve questions on recognition and communication during pollen-pistil interactions in the extended tomato family. In this context, this work was initiated and planned to study the potential involvement of tomato pollen-specific receptor-like kinases (RLK's) in the interaction between pollen and pistils. By special permission from BARD the objectives of this research were extended to include studies on pollen-pistil interactions and pollination barriers in horticultural crops with an emphasis on citrus. Functional characterization of 2 pollen-specific RLK's from tomato was carried out. The data shows that both encode functional kinases that were active as recombinant proteins. One of the kinases was shown to accumulate mainly after pollen germination and to be phosphorylated in-vitro in pollen membranes as well as in-vivo. The presence of style extract resulted in dephosphorylation of the RLK, although no species specificity was observed. This data implies a role for at least one RLK in pollination events following pollen germination. However, a transgenic plant analysis of the RLK's comprising overexpression, dominant-negative and anti-sense constructs failed to provide answers on their role in pollination. While genetic effects on some of the plants were observed in both the Israeli and American labs, no clear functional answers were obtained. An alternative approach to addressing function was pursued by screening for an artificial ligand for the receptor domain using a peptide phage display library. An enriched peptide sequence was obtained and will be used to design a peptide-ligand to be tested for its effect o pollen germination and tube growth. Self-incompatibility (SI) in citrus was studied on 3 varieties of pummelo. SI was observed using fluorescence microscopy in each of the 3 varieties and compatibility relations between varieties was determined. An initial screen for an S-RNase SI mechanism yielded only a cDNA homologous to the group of S-like RNases, suggesting that SI results from an as yet unknown mechanism. 2D gel electrophoresis was applied to compare pollen and style profiles of different compatibility groups. A "polymorphic" protein band from style extracts was observed, isolated and micro-sequenced. Degenerate primers designed based on the peptide sequence date will be used to isolate the relevant genes i order to study their potential involvement in SI. A study on SI in the apple cultivar Top red was initiated. SI was found, as previously shown, to be complete thus requiring a compatible pollinator variety. A new S-RNase allele was discovered fro Top red styles and was found to be highly homologous to pear S-RNases, suggesting that evolution of these genes pre-dated speciation into apples and pears but not to other Rosaceae species. The new allele provides molecular-genetic tools to determine potential pollinators for the variety Top red as well as a tool to break-down SI in this important variety.

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Beavers. L51557 Pressure Losses in Compressor Station Yard Pipework - Phase II. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), juin 1987. http://dx.doi.org/10.55274/r0010277.

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The economic assessment of piping layout in compressor station yards relies on accurate prediction of pressure losses within the network. Methods currently used to predict pressure losses in station pipe work are unreliable. As a result inadequate and inaccurate information is being used when making economic assessments of piping layout and in the prediction of operating costs. By improving the design process substantial economic advantages may be gained in balancing pressure losses and compressor inlet flow conditions against investment in piping and components. Currently the existing data concentrate on isolated component losses and there is a lack of reliable data on interaction of adjacent components frequently present in compressor yard layouts. Thus, in order to produce a comprehensive guide to compressor yard losses, there was considerable incentive to quantify these interactions. This report details the experimental work to provide reliable pressure loss data for an engineer's design handbook. The tee tests include the effect of branch to run radius and two area ratios. A total of 36 bend/tee combinations were tested. Results are presented as overall bend/tee pressure loss coefficients and interaction corrections. The latter are used in the design handbook. The factors affecting bend and tee performance are discussed. Bend/tee interactions are explained qualitatively in terms of interaction of the pressure and flow distributions within the components. The work covers pressure losses in bends, close coupled bend/bend combinations, tees (combining and dividing) and tee/bend combinations.

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Leibowitz, L. Phase relations for fuel-cladding interactions. Office of Scientific and Technical Information (OSTI), octobre 1986. http://dx.doi.org/10.2172/712838.

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Chen, Weixing. PR-378-083601-R02 Effect of Pressure Fluctuations on Growth Rate of Near-Neutral pH SCC. Chantilly, Virginia : Pipeline Research Council International, Inc. (PRCI), août 2017. http://dx.doi.org/10.55274/r0011010.

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This report summarizes the work completed in Phase 1 and Phase 2 of PRCI SCC-2-12 project: Effect of Pressure Fluctuations on Growth Rate of Near-Neutral pH SCC. The following two insights from the two-phase PRCI SCC 2-12 project can be proven to be the most important: 1) The identification of three types of pressure fluctuations and their different susceptibility to crack growth; 2) The importance of load interaction effects during variable amplitude pressure fluctuations in the prediction of crack growth rate. The work has enabled us to divide near-neutral pH SCC cracking into the following two governing processes: the dissolution growth process for crack initiation and early stage crack growth and the hydrogen facilitated fatigue growth after crack initiation and dormancy. The first process features very high rate of dissolution at the pipe surface caused by various forms of galvanic processes and reduced crack growth in the depth direction leading to crack dormancy. The hydrogen facilitated fatigue growth process has been determined to be predominant for the crack growth after crack initiation and dormancy. Depending on the location of pipeline sections, the pressure fluctuations could be characterized into three types based on the relative pressure levels of the large loading events and the minor cycles. It has been determined from extensive experimental investigations that crack growth under Type I pressure fluctuations with frequent underload cycles, which is often found within 30 km downstream of a compressor station, can be enhanced significantly because of effects of load interactions of variable amplitude of cyclic loading. The load-interactions during SCC of pipeline steels in near-neutral pH environments are complex, which include both the time independent load-history interactions and the time dependent load interactions related to the rate of diffusion of hydrogen and hydrogen embrittlement in response to various scenarios of pressure fluctuations. Based on the experimental findings obtained, strategies for mitigating near-neutral pH crack initiation and crack growth during field operations have been proposed. The experimental findings have also been integrated into a software, namely the Pipe-Online, for making crack growth and remaining life prediction. For the purpose of capturing all the crack-growth contributing events of pressure fluctuations for life predictions, a method of recording pressure fluctuations has also been developed.

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Melville, W. K. Wave-Phase-Resolved Air-Sea Interaction. Fort Belvoir, VA : Defense Technical Information Center, septembre 2014. http://dx.doi.org/10.21236/ada618050.

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A.S. Grader, D. Elsworth, P.M. Halleck, F. Alvarado, A. Alajmi, Z. Karpyn, N. Mohammed et S. Al-Enezi. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES. Office of Scientific and Technical Information (OSTI), juin 2005. http://dx.doi.org/10.2172/841611.

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A.S. Grader, D. Elsworth, P.M. Halleck, F. Alvarao, A. Alajmi, Z. Karpyn, N. Mohammed et S. Al-Enezi. Multi-Phase Fracture-Matrix Interactions Under Stress Changes. Office of Scientific and Technical Information (OSTI), décembre 2005. http://dx.doi.org/10.2172/876472.

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A.S. Grader, D. Elsworth, P.M. Halleck, F. Alvarad, H. Yasuhara et A. Alajmi. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES. Office of Scientific and Technical Information (OSTI), avril 2002. http://dx.doi.org/10.2172/813455.

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