49 results on '"Margaret McFALL"'
Search Results
2. Microbiomes and metabolomes of dominant coral reef primary producers illustrate a potential role for immunolipids in marine symbioses
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Helena Mannochio-Russo, Sean O. I. Swift, Kirsten K. Nakayama, Christopher B. Wall, Emily C. Gentry, Morgan Panitchpakdi, Andrés M. Caraballo-Rodriguez, Allegra T. Aron, Daniel Petras, Kathleen Dorrestein, Tatiana K. Dorrestein, Taylor M. Williams, Eileen M. Nalley, Noam T. Altman-Kurosaki, Mike Martinelli, Jeff Y. Kuwabara, John L. Darcy, Vanderlan S. Bolzani, Linda Wegley Kelly, Camilo Mora, Joanne Y. Yew, Anthony S. Amend, Margaret McFall-Ngai, Nicole A. Hynson, Pieter C. Dorrestein, and Craig E. Nelson
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Biology (General) ,QH301-705.5 - Abstract
Abstract The dominant benthic primary producers in coral reef ecosystems are complex holobionts with diverse microbiomes and metabolomes. In this study, we characterize the tissue metabolomes and microbiomes of corals, macroalgae, and crustose coralline algae via an intensive, replicated synoptic survey of a single coral reef system (Waimea Bay, Oʻahu, Hawaii) and use these results to define associations between microbial taxa and metabolites specific to different hosts. Our results quantify and constrain the degree of host specificity of tissue metabolomes and microbiomes at both phylum and genus level. Both microbiome and metabolomes were distinct between calcifiers (corals and CCA) and erect macroalgae. Moreover, our multi-omics investigations highlight common lipid-based immune response pathways across host organisms. In addition, we observed strong covariation among several specific microbial taxa and metabolite classes, suggesting new metabolic roles of symbiosis to further explore.
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- 2023
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3. Bioluminescence in cephalopods: biodiversity, biogeography and research trends
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Eve Otjacques, Vasco Pissarra, Kathrin Bolstad, José C. Xavier, Margaret McFall-Ngai, and Rui Rosa
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bioluminescence ,mollusks ,Cephalopoda ,diversity ,distribution ,systematic review ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Numerous terrestrial and marine organisms, including cephalopods, are capable of light emission. In addition to communication, bioluminescence is used for attraction and defense mechanisms. The present review aims to: (i) present updated information on the taxonomic diversity of luminous cephalopods and morphological features, (ii) describe large-scale biogeographic patterns, and (iii) show the research trends over the last 50 years on cephalopod bioluminescence. According to our database (834 species), 32% of all known cephalopod species can emit light, including oegopsid and myopsid squids, sepiolids, octopuses, and representatives of several other smaller orders (bathyteuthids, and the monotypic vampire “squid”, Vampyroteuthis infernalis and ram’s horn “squid”, Spirula spirula). Most species have a combination of photophores present in different locations, of which light organs on the head region are dominant, followed by photophores associated with the arms and tentacles and internal photophores. Regarding the biogeographic patterns of cephalopod species with light organs, the most diverse ocean is the Pacific Ocean, followed by the Atlantic and Indian Oceans. The least diverse are the Southern and the Arctic Oceans. Regarding publication trends, our systematic review revealed that, between 1971 and 2020, 277 peer-reviewed studies were published on bioluminescent cephalopods. Most research has been done on a single species, the Hawaiian bobtail squid Euprymna scolopes. The interest in this species is mostly due to its species-specific symbiotic relationship with the bacterium Vibrio fischeri, which is used as a model for the study of Eukaryote–Prokaryote symbiosis. Because there are many knowledge gaps about the biology and biogeography of light-producing cephalopods, new state-of-the-art techniques (e.g., eDNA for diversity research and monitoring) can help achieve a finer resolution on species’ distributions. Moreover, knowledge on the effects of climate change stressors on the bioluminescent processes is nonexistent. Future studies are needed to assess such impacts at different levels of biological organization, to describe the potential broad-scale biogeographic changes, and understand the implications for food web dynamics.
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- 2023
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4. Ciliated epithelia are key elements in the recruitment of bacterial partners in the squid-vibrio symbiosis
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Katrina A. Gundlach, Janna Nawroth, Eva Kanso, Farzana Nasrin, Edward G. Ruby, and Margaret McFall-Ngai
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ciliated fields ,symbiont harvesting ,Euprymna scolopes ,Vibrio fischeri ,light organ ,ciliary beat frequency ,Biology (General) ,QH301-705.5 - Abstract
The Hawaiian bobtail squid, Euprymna scolopes, harvests its luminous symbiont, Vibrio fischeri, from the surrounding seawater within hours of hatching. During embryogenesis, the host animal develops a nascent light organ with ciliated fields on each lateral surface. We hypothesized that these fields function to increase the efficiency of symbiont colonization of host tissues. Within minutes of hatching from the egg, the host’s ciliated fields shed copious amounts of mucus in a non-specific response to bacterial surface molecules, specifically peptidoglycan (PGN), from the bacterioplankton in the surrounding seawater. Experimental manipulation of the system provided evidence that nitric oxide in the mucus drives an increase in ciliary beat frequency (CBF), and exposure to even small numbers of V. fischeri cells for short periods resulted in an additional increase in CBF. These results indicate that the light-organ ciliated fields respond specifically, sensitively, and rapidly, to the presence of nonspecific PGN as well as symbiont cells in the ambient seawater. Notably, the study provides the first evidence that this induction of an increase in CBF occurs as part of a thus far undiscovered initial phase in colonization of the squid host by its symbiont, i.e., host recognition of V. fischeri cues in the environment within minutes. Using a biophysics-based mathematical analysis, we showed that this rapid induction of increased CBF, while accelerating bacterial advection, is unlikely to be signaled by V. fischeri cells interacting directly with the organ surface. These overall changes in CBF were shown to significantly impact the efficiency of V. fischeri colonization of the host organ. Further, once V. fischeri has fully colonized the host tissues, i.e., about 12–24 h after initial host-symbiont interactions, the symbionts drove an attenuation of mucus shedding from the ciliated fields, concomitant with an attenuation of the CBF. Taken together, these findings offer a window into the very first interactions of ciliated surfaces with their coevolved microbial partners.
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- 2022
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5. Evidence of Genomic Diversification in a Natural Symbiotic Population Within Its Host
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Clotilde Bongrand, Eric Koch, Daniel Mende, Anna Romano, Susannah Lawhorn, Margaret McFall-Ngai, Edward F. DeLong, and Edward G. Ruby
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Vibrio fischeri ,comparative genomic ,Euprymna scolopes ,symbiosis ,population biology ,Microbiology ,QR1-502 - Abstract
Planktonic cells of the luminous marine bacterium Vibrio fischeri establish themselves in the light-emitting organ of each generation of newly hatched Euprymna scolopes bobtail squid. A symbiont population is maintained within the 6 separated crypts of the organ for the ∼9-month life of the host. In the wild, the initial colonization step is typically accomplished by a handful of planktonic V. fischeri cells, leading to a species-specific, but often multi-strain, symbiont population. Within a few hours, the inoculating cells proliferate within the organ’s individual crypts, after which there is evidently no supernumerary colonization. Nevertheless, every day at dawn, the majority of the symbionts is expelled, and the regrowth of the remaining ∼5% of cells provides a daily opportunity for the population to evolve and diverge, thereby increasing its genomic diversity. To begin to understand the extent of this diversification, we characterized the light-organ population of an adult animal. First, we used 16S sequencing to determine that species in the V. fischeri clade were essentially the only ones detectable within a field-caught E. scolopes. Efforts to colonize the host with a minor species that appeared to be identified, V. litoralis, revealed that, although some cells could be imaged within the organ, they were
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- 2022
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6. Getting the Message Out: the Many Modes of Host-Symbiont Communication during Early-Stage Establishment of the Squid-Vibrio Partnership
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Margaret McFall-Ngai and Edward Ruby
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horizontal transmission ,microbiome ,development ,signal/cue ,animal development ,Microbiology ,QR1-502 - Abstract
ABSTRACT Symbiosis, by its basic nature, depends on partner interactions that are mediated by cues and signals. This kind of critical reciprocal communication shapes the trajectory of host-microbe associations from their onset through their maturation and is typically mediated by both biochemical and biomechanical influences. Symbiotic partnerships often involve communities composed of dozens to hundreds of microbial species, for which resolving the precise nature of these partner interactions is highly challenging. Naturally occurring binary associations, such as those between certain legumes, nematodes, fishes, and squids, and their specific bacterial partner species offer the opportunity to examine interactions with high resolution and at the scale at which the interactions occur. The goals of this review are to provide the conceptual framework for evolutionarily conserved drivers of host-symbiont communication in animal associations and to offer a window into some mechanisms of this phenomenon as discovered through the study of the squid-vibrio model. The discussion focuses upon the early events that lead to persistence of the symbiotic partnership. The biophysical and biochemical determinants of the initial hours of dialogue between partners and how the symbiosis is shaped by the environment that is created by their reciprocal interactions are key topics that have been difficult to approach in more complex systems. Through our research on the squid-vibrio system, we provide insight into the intricate temporal and spatial complexity that underlies the molecular and cellular events mediating successful microbial colonization of the host animal.
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- 2021
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7. Using Colonization Assays and Comparative Genomics To Discover Symbiosis Behaviors and Factors in Vibrio fischeri
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Clotilde Bongrand, Silvia Moriano-Gutierrez, Philip Arevalo, Margaret McFall-Ngai, Karen L. Visick, Martin Polz, and Edward G. Ruby
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Vibrio (Aliivibrio) fischeri ,genomes ,dominance ,symbiosis ,intraspecific ,Aliivibrio ,Microbiology ,QR1-502 - Abstract
ABSTRACT The luminous marine Gram-negative bacterium Vibrio (Aliivibrio) fischeri is the natural light organ symbiont of several squid species, including the Hawaiian bobtail squid, Euprymna scolopes, and the Japanese bobtail squid, Euprymna morsei. Work with E. scolopes has shown how the bacteria establish their niche in the light organ of the newly hatched host. Two types of V. fischeri strains have been distinguished based upon their behavior in cocolonization competition assays in juvenile E. scolopes, i.e., (i) niche-sharing or (ii) niche-dominant behavior. This study aimed to determine whether these behaviors are observed with other V. fischeri strains or whether they are specific to those isolated from E. scolopes light organs. Cocolonization competition assays between V. fischeri strains isolated from the congeneric squid E. morsei or from other marine animals revealed the same sharing or dominant behaviors. In addition, whole-genome sequencing of these strains showed that the dominant behavior is polyphyletic and not associated with the presence or absence of a single gene or genes. Comparative genomics of 44 squid light organ isolates from around the globe led to the identification of symbiosis-specific candidates in the genomes of these strains. Colonization assays using genetic derivatives with deletions of these candidates established the importance of two such genes in colonization. This study has allowed us to expand the concept of distinct colonization behaviors to strains isolated from a number of squid and fish hosts. IMPORTANCE There is an increasing recognition of the importance of strain differences in the ecology of a symbiotic bacterial species and, in particular, how these differences underlie crucial interactions with their host. Nevertheless, little is known about the genetic bases for these differences, how they manifest themselves in specific behaviors, and their distribution among symbionts of different host species. In this study, we sequenced the genomes of Vibrio fischeri isolated from the tissues of squids and fishes and applied comparative genomics approaches to look for patterns between symbiont lineages and host colonization behavior. In addition, we identified the only two genes that were exclusively present in all V. fischeri strains isolated from the light organs of sepiolid squid species. Mutational studies of these genes indicated that they both played a role in colonization of the squid light organ, emphasizing the value of applying a comparative genomics approach in the study of symbioses.
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- 2020
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8. Reply to 'Improving Microbiology Research: the Problems Are Less Statistical and More Biological'
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Arturo Casadevall, Lee M. Ellis, Erika W. Davies, Margaret McFall-Ngai, and Ferric C. Fang
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Microbiology ,QR1-502 - Published
- 2016
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9. A Framework for Improving the Quality of Research in the Biological Sciences
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Arturo Casadevall, Lee M. Ellis, Erika W. Davies, Margaret McFall-Ngai, and Ferric C. Fang
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Microbiology ,QR1-502 - Abstract
ABSTRACT The American Academy of Microbiology convened a colloquium to discuss problems in the biological sciences, with emphasis on identifying mechanisms to improve the quality of research. Participants from various disciplines made six recommendations: (i) design rigorous and comprehensive evaluation criteria to recognize and reward high-quality scientific research; (ii) require universal training in good scientific practices, appropriate statistical usage, and responsible research practices for scientists at all levels, with training content regularly updated and presented by qualified scientists; (iii) establish open data at the timing of publication as the standard operating procedure throughout the scientific enterprise; (iv) encourage scientific journals to publish negative data that meet methodologic standards of quality; (v) agree upon common criteria among scientific journals for retraction of published papers, to provide consistency and transparency; and (vi) strengthen research integrity oversight and training. These recommendations constitute an actionable framework that, in combination, could improve the quality of biological research.
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- 2016
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10. Introduction to the Hologenome Special Series
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Margaret McFall-Ngai
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Microbiology ,QR1-502 - Published
- 2016
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11. Divining the essence of symbiosis: insights from the squid-vibrio model.
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Margaret McFall-Ngai
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Biology (General) ,QH301-705.5 - Abstract
Biology has a big elephant in the room. Researchers are learning that microorganisms are critical for every aspect of the biosphere's health. Even at the scale of our own bodies, we are discovering the unexpected necessity and daunting complexity of our microbial partners. How can we gain an understanding of the form and function of these "ecosystems" that are an individual animal? This essay explores how development of experimental model systems reveals basic principles that underpin the essence of symbiosis and, more specifically, how one symbiosis, the squid-vibrio association, provides insight into the persistent microbial colonization of animal epithelial surfaces.
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- 2014
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12. A New Design for the ASM General Meeting
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Jeff F. Miller, Margaret McFall-Ngai, and Arturo Casadevall
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Microbiology ,QR1-502 - Published
- 2010
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13. Symbiotic organs shaped by distinct modes of genome evolution in cephalopods
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Mahdi Belcaid, Giorgio Casaburi, Sarah J. McAnulty, Hannah Schmidbaur, Andrea M. Suria, Silvia Moriano-Gutierrez, M. Sabrina Pankey, Todd H. Oakley, Natacha Kremer, Eric J. Koch, Andrew J. Collins, Hoan Nguyen, Sai Lek, Irina Goncharenko-Foster, Patrick Minx, Erica Sodergren, George Weinstock, Daniel S. Rokhsar, Margaret McFall-Ngai, Oleg Simakov, Jamie S. Foster, and Spencer V. Nyholm
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- 2019
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14. A peptidoglycan-recognition protein orchestrates the first steps of symbiont recruitment in the squid-vibrio symbiosis
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Caleb-Matthew Olaso, Joani Viliunas, and Margaret McFall-Ngai
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General Agricultural and Biological Sciences ,Article - Abstract
In symbioses established through horizontal transmission, evolution has selected for mechanisms that promote the recruitment of symbionts from the environment. Using the binary association between the Hawaiian bobtail squid, Euprymna scolopes, and its symbiont, Vibrio fischeri, we explored the first step of symbiont enrichment around sites where V. fischeri cells will enter host tissues. Earlier studies of the system had shown that, within minutes of hatching in natural seawater, ciliated epithelia of the nascent symbiotic tissue secrete a layer of mucus in response to exposure to the cell-wall biomolecule peptidoglycan (PGN) from non-specific bacterioplankton. We hypothesized that a peptidoglycan recognition protein, EsPGRP4, is the receptor that mediates host mucus secretion by sensing the environmental PGN; earlier studies of this protein family had shown that this is the only member predicted to behave as a membrane receptor. Immunocytochemistry localized EsPGRP4 to the superficial ciliated fields of the juvenile organ. We found that production of EsPGRP4 increased over the first 48 h after hatching if the light organ remained uncolonized. When colonized by V. fischeri, the levels of the protein in light-organ tissue remained similar to that of hatchling organs. Pharmacologically curing the initially colonized light organ with antibiotics resulted in return of EsPGRP4 production to levels similar to light organs that had remained uncolonized since hatching. Furthermore, we found that preincubation of the tissues with an EsPGRP4 antibody decreased light organ mucus production and colonization. These findings provide evidence of an innate mechanism that underlies a crucial first step in the horizontal recruitment of bacterial symbionts.
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- 2022
15. Flow Physics Explains Morphological Diversity of Ciliated Organs
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Janna C. Nawroth, Feng Ling, Tara Essock-Burns, David Stein, Margaret McFall-Ngai, Kakani Katija, Michael J. Shelley, and Eva Kanso
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Ciliated organs that pump luminal fluids are integral to animal physiology. Such organs, including the human airways and reproductive tracts, feature ciliated ducts that direct internal flows. Although cilia organization and duct morphology vary drastically in the animal kingdom, ducts are typically classified into two, seemingly disconnected, archetypes: the familiar carpet and the intriguing flame designs. The reason behind this dichotomy and how duct design relates to fluid pumping remain unclear. Here, we apply morphometric and mechanistic analyses to ciliated ducts across all animal phyla. We find that two structural parameters, lumen diameter and cilia-to-lumen ratio, organize the observed duct diversity into a continuous spectrum that connects carpets to flames. Using a unified fluid model, we discover that carpets and flames, respectively, maximize flow rate and pressure generation, which is consistent with physiological requirements for bulk transport and filtration, whereas intermediate designs along the morphological spectrum constitute optimally efficient hybrids. We propose that convergence of ciliated organ designs follows functional constraints rather than phylogenetic distance, and we present universal design rules for ciliary pumps.
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- 2023
16. The mud-dwelling clam Meretrix petechialis secretes endogenously synthesized erythromycin
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Xin Yue, Shujing Zhang, Hongxia Wang, Jiajia Yu, Quancai Peng, Margaret McFall-Ngai, and Baozhong Liu
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Multidisciplinary - Abstract
Although lacking an adaptive immune system and often living in habitats with dense and diverse bacterial populations, marine invertebrates thrive in the presence of potentially challenging microbial pathogens. However, the mechanisms underlying this resistance remain largely unexplored and promise to reveal novel strategies of microbial resistance. Here, we provide evidence that a mud-dwelling clam, Meretrix petechiali s, synthesizes, stores, and secretes the antibiotic erythromycin. Liquid chromatography coupled with mass spectrometry, immunocytochemistry, fluorescence in situ hybridization, RNA interference, and enzyme-linked immunosorbent assay revealed that this potent macrolide antimicrobial, thought to be synthesized only by microorganisms, is produced by specific mucus-rich cells beneath the clam’s mantle epithelium, which interfaces directly with the bacteria-rich environment. The antibacterial activity was confirmed by bacteriostatic assay. Genetic, ontogenetic, phylogenetic and genomic evidence, including genotypic segregation ratios in a family of full siblings, gene expression in clam larvae, phylogenetic tree, and synteny conservation in the related genome region further revealed that the genes responsible for erythromycin production are of animal origin. The detection of this antibiotic in another clam species showed that the production of this macrolide is not exclusive to M. petechialis and may be a common strategy among marine invertebrates. The finding of erythromycin production by a marine invertebrate offers a striking example of convergent evolution in secondary metabolite synthesis between the animal and bacterial domains. These findings open the possibility of engineering-animal tissues for the localized production of an antibacterial secondary metabolite.
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- 2022
17. A ridge-to-reef ecosystem microbial census reveals environmental reservoirs for animal and plant microbiomes
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Anthony S. Amend, Sean O. I. Swift, John L. Darcy, Mahdi Belcaid, Craig E. Nelson, Joshua Buchanan, Nicolas Cetraro, Kauaoa M. S. Fraiola, Kiana Frank, Kacie Kajihara, Terrance G. McDermot, Margaret McFall-Ngai, Matthew Medeiros, Camilo Mora, Kirsten K. Nakayama, Nhu H. Nguyen, Randi L. Rollins, Peter Sadowski, Wesley Sparagon, Mélisandre A. Téfit, Joanne Y. Yew, Danyel Yogi, and Nicole A. Hynson
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Multidisciplinary ,Bacteria ,Microbiota ,Animals ,Plants ,Ecosystem - Abstract
Microbes are found in nearly every habitat and organism on the planet, where they are critical to host health, fitness, and metabolism. In most organisms, few microbes are inherited at birth; instead, acquiring microbiomes generally involves complicated interactions between the environment, hosts, and symbionts. Despite the criticality of microbiome acquisition, we know little about where hosts’ microbes reside when not in or on hosts of interest. Because microbes span a continuum ranging from generalists associating with multiple hosts and habitats to specialists with narrower host ranges, identifying potential sources of microbial diversity that can contribute to the microbiomes of unrelated hosts is a gap in our understanding of microbiome assembly. Microbial dispersal attenuates with distance, so identifying sources and sinks requires data from microbiomes that are contemporary and near enough for potential microbial transmission. Here, we characterize microbiomes across adjacent terrestrial and aquatic hosts and habitats throughout an entire watershed, showing that the most species-poor microbiomes are partial subsets of the most species-rich and that microbiomes of plants and animals are nested within those of their environments. Furthermore, we show that the host and habitat range of a microbe within a single ecosystem predicts its global distribution, a relationship with implications for global microbial assembly processes. Thus, the tendency for microbes to occupy multiple habitats and unrelated hosts enables persistent microbiomes, even when host populations are disjunct. Our whole-watershed census demonstrates how a nested distribution of microbes, following the trophic hierarchies of hosts, can shape microbial acquisition.
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- 2022
18. Building a career during a revolution in biology
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Margaret McFall-Ngai
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Microbiology (medical) ,Immunology ,Genetics ,Cell Biology ,Applied Microbiology and Biotechnology ,Microbiology - Published
- 2022
19. Opinion: Why science needs philosophy
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Lucie Laplane, Paolo Mantovani, Ralph Adolphs, Hasok Chang, Alberto Mantovani, Margaret McFall-Ngai, Carlo Rovelli, Elliott Sober, Thomas Pradeu
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- 2019
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20. Evaluation of Antimicrobial Resistance Profiles of Escherichia coli Isolates of Broiler Chickens at Slaughter in Alberta, Canada
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Chunu Mainali, Robin King, Rebecca Irwin, and Margaret McFall
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Colony Count, Microbial ,Food Contamination ,Microbial Sensitivity Tests ,Biology ,Microbiology ,Alberta ,Antibiotic resistance ,Drug Resistance, Multiple, Bacterial ,Drug Resistance, Bacterial ,Escherichia coli ,Prevalence ,medicine ,Animals ,Humans ,Dose-Response Relationship, Drug ,Broth microdilution ,Kanamycin ,biochemical phenomena, metabolism, and nutrition ,Antimicrobial ,Anti-Bacterial Agents ,Multiple drug resistance ,Ciprofloxacin ,Consumer Product Safety ,Streptomycin ,Amikacin ,Chickens ,Food Science ,medicine.drug - Abstract
This study was conducted to investigate antimicrobial resistance profiles of Escherichia coli isolates from broiler chickens in Alberta, Canada. Cecal contents of broiler chickens from 24 flocks were collected at slaughter between January and March 2005 for culture and antimicrobial susceptibility testing against a panel of 15 antimicrobials using a broth microdilution technique. Of 600 E. coli isolates tested, 475 (79.2%) were resistant to one or more antimicrobials, 326 (54.3%) were resistant to three or more antimicrobials, 65 (10.8%) were resistant to five or more antimicrobials, and 15 (2.5%) were resistant to seven or more antimicrobials. The most common resistance was to tetracycline (69.2%), followed by streptomycin (48.2%), kanamycin (40.3%), and sulfisoxazole (38.0%). None of the E. coli isolates were resistant to amikacin, ceftriaxone, or ciprofloxacin. Of the isolates that were resistant to two or more antimicrobials, the most common multidrug resistance patterns were streptomycinte-tracycline (44.0%), streptomycin-sulfisoxazole-tetracycline (30.7%), and kanamycin-streptomycin-sulfisoxazole-tetracycline (23.5%). Resistance to tetracycline and kanamycin (odds ratio = 46.7, P = 0.0001) was highly associated, followed by resistance to streptomycin and sulfisoxazole (odds ratio = 12.0, P = 0.0001), and streptomycin and tetracycline (odds ratio = 10.3, P = 0.0001). The flock level prevalence of resistance varied from 16.7% for chloramphenicol to 100.0% for ampicillin, streptomycin, sulfisoxazole, and tetracycline. The results of this study provided baseline information on antimicrobial susceptibility of E. coli isolates of broiler chickens at slaughter in Alberta, which can serve as a bench mark for future research.
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- 2013
21. Comparison of Bacterial Culture and Real-Time PCR for the Detection of Salmonella in Grow-Finish Pigs in Western Canada Using a Bayesian Approach
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Anne Muckle, Andrijana Rajić, Cheryl L. Waldner, Margaret McFall, Raúl C. Mainar-Jaime, and W. Wilkins
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Serotype ,Veterinary medicine ,Salmonella ,Microbiological culture ,General Veterinary ,General Immunology and Microbiology ,Epidemiology ,Public Health, Environmental and Occupational Health ,Biology ,medicine.disease_cause ,Agar plate ,Bayes' theorem ,Infectious Diseases ,medicine ,Herd ,Food microbiology ,Feces - Abstract
The study objective was to evaluate the accuracy of a real-time polymerase chain reaction (RT-PCR) and a culture protocol used to detect Salmonella in the faeces of grow-finish pigs using a Bayesian approach. The RT-PCR was invA-gene-based assay, while the culture protocol included pre-enrichment in buffered peptone water, selective enrichment in tetrathionate and Rappaport-Vassiliadis broths, and isolation on semi-solid (modified semi-solid RV) or solid (XLT4, Rambach) agar plates. Bayesian analysis was performed using a two-test, two-population model with dependence between culture and RT-PCR and compared to a second model with conditional independence between these two tests. Two hundred and ninety three individual faecal and 294 pooled pen samples from grow-finish pig collected from 10 farms were tested and results were divided into two groups according to herd size (five herds 400 sows). In the dependence model, RT-PCR sensitivity (Se) and specificity (Sp) were estimated to be 90% (95% probability interval 74, 97) and 99% (98, 99), respectively. Culture Se was 92% (75, 99), while culture Sp was considered 100% as all culture-positive samples were confirmed by serotyping. In the conditional independence model, RT-PCR Se and Sp, and culture Se, were 96% (93, 98), 99% (98, 100) and 97% (94, 100), respectively. The dependence model resulted in posterior estimates of Se that were lower and with broader probability intervals than the independence model, indicating that when RT-PCR and culture are evaluated relative to each other, the correlation between these tests is an important source of bias and should be adjusted for during analysis. The RT-PCR evaluated in this study performed almost comparably to culture; given the cost savings associated with using this test and more timely results, the RT-PCR may be a useful alternative to culture for screening large numbers of samples, particularly when Salmonella prevalence is low.
- Published
- 2010
22. A Real-Time PCR Assay for the Detection of Salmonella in a Wide Variety of Food and Food-Animal Matrices
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Gary Gensler, Robin King, Valerie M. Bohaychuk, David G. Renter, and Margaret McFall
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Salmonella ,Time Factors ,Swine ,Colony Count, Microbial ,Food Contamination ,medicine.disease_cause ,Polymerase Chain Reaction ,Sensitivity and Specificity ,Microbiology ,Enrichment culture ,Fluorescence ,Poultry ,law.invention ,law ,medicine ,Animals ,Humans ,Food microbiology ,Horses ,Feces ,Polymerase chain reaction ,Skin ,biology ,Nucleic Acid Hybridization ,Reproducibility of Results ,biology.organism_classification ,Isolation (microbiology) ,Animal Feed ,Enterobacteriaceae ,Consumer Product Safety ,Food Microbiology ,Cattle ,DNA Probes ,Bacteria ,Food Science - Abstract
Conventional culture methods have traditionally been considered the "gold standards" for the isolation and identification of foodborne pathogens. However, culture methods are labor-intensive and time-consuming. We have developed a real-time PCR assay for the detection of Salmonella in a variety of food and food-animal matrices. The real-time PCR assay incorporates both primers and hybridization probes based on the sequence of the Salmonella invA gene and uses fluorescent resonance energy transfer technology to ensure highly sensitive and specific results. This method correctly classified 51 laboratory isolates of Salmonella and 28 non-Salmonella strains. The method was also validated with a large number of field samples that consisted of porcine feces and cecal contents, pork carcasses, bovine feces and beef carcasses, poultry cecal contents and carcasses, equine feces, animal feeds, and various food products. The samples (3388) were preenriched in buffered peptone water and then selectively enriched in tetrathionate and Rappaport-Vassiliadis broths. Aliquots of the selective enrichment broths were combined for DNA extraction and analysis by the real-time PCR assay. When compared with the culture method, the diagnostic sensitivity of the PCR assay for the various matrices ranged from 97.1 to 100.0%, and the diagnostic specificity ranged from 91.3 to 100.0%. Kappa values ranged from 0.87 to 1.00, indicating excellent agreement of the real-time PCR assay to the culture method. The reduction in time and labor makes this highly sensitive and specific real-time PCR assay an excellent alternative to conventional culture methods for surveillance and research studies to improve food safety.
- Published
- 2007
23. Longitudinal study of Salmonella species in 90 Alberta swine finishing farms
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Catherine E. Dewey, Julia Keenliside, Anne E. Deckert, Brendan P. O’Connor, Andrijana Rajiċ, Ken Manninen, Anne C. Muckle, Scott A. McEwen, and Margaret McFall
- Subjects
Serotype ,Salmonella ,Veterinary medicine ,Swine ,animal diseases ,Biology ,medicine.disease_cause ,Microbiology ,Alberta ,Feces ,medicine ,Animals ,Longitudinal Studies ,Serotyping ,Bacteriophage Typing ,Swine Diseases ,Salmonella Infections, Animal ,Positive sample ,Salmonella species ,General Veterinary ,Annual production ,Follow up studies ,General Medicine ,Status changed - Abstract
The aim of this study was to determine the farm prevalence of Salmonella in 90 Alberta finishing swine farms over a 5-month period, to evaluate Salmonella distribution in the farm environment and to describe Salmonella serovar diversity on these farms. Ten veterinary practitioners selected 90 Alberta swine farms based on an annual production of ≥2000 market pigs per farm and the willingness of the producers to participate in the study. Between May and September 2000, twenty samples were collected from finishing swine and the environment of each farm. The annual production of selected farms represented approximately 25% of the market swine production in Alberta. Participating farms were geographically representative of major swine production areas in Alberta. Sixty (66.7%) farms had at least one Salmonella -positive sample, with confidence interval (CI) of 57.1–77.2%. Salmonella were detected in 14.3% of fecal and 20.1% of environmental samples. The number of Salmonella- positive samples per farm ranged from 1 to 19. Among environmental samples, Salmonella were most frequently recovered from boots (38.6%) and the main drain (31.8%). Twenty-two serovars were detected on the 60 Salmonella -positive farms. Serovars Typhimurium (78 isolates), Derby (71 isolates) and Infantis (47 isolates) were the most common. A single serovar was detected on 58 farms, while 2, 3 and >3 serovars were detected on 15, 10 and 7 farms, respectively. The Salmonella farm status changed frequently over the 5-month period indicating the dynamic nature of Salmonella infections on these farms.
- Published
- 2005
24. Evaluation of antimicrobial resistance profiles of Salmonella isolates from broiler chickens at slaughter in Alberta, Canada
- Author
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Margaret McFall, Robin King, Rebecca Irwin, and C. Mainali
- Subjects
Salmonella ,Meat ,Nalidixic acid ,Tetracycline ,Colony Count, Microbial ,Microbial Sensitivity Tests ,Biology ,medicine.disease_cause ,Microbiology ,Alberta ,Antibiotic resistance ,Ampicillin ,Drug Resistance, Multiple, Bacterial ,medicine ,Prevalence ,Animals ,Humans ,Dose-Response Relationship, Drug ,Antimicrobial ,Anti-Bacterial Agents ,Amikacin ,Consumer Product Safety ,Food Microbiology ,Female ,Ceftiofur ,Chickens ,Food Science ,medicine.drug - Abstract
Antimicrobial-resistant Salmonella species are threatening to become a serious public health problem. Therefore, surveillance and prudent use of antimicrobials is needed in both the agricultural and human health sectors. The aim of this study was to describe the antimicrobial susceptibility profiles of Salmonella isolates recovered from healthy broiler chickens at slaughter from November 2004 to April 2005. Salmonella isolates recovered from 36 broiler flocks in Alberta, Canada, were serotyped and tested for antimicrobial susceptibility against 15 antimicrobials. Of 272 Salmonella isolates tested, 64.0% were resistant to one or more antimicrobials, 10.0% were resistant to three or more antimicrobials, and 1.8% were resistant to five antimicrobials. All isolates were susceptible to amikacin, amoxicillin-clavulanic acid, ceftiofur, cefoxitin, ceftriaxone, ciprofloxacin, and nalidixic acid. The highest prevalence of resistance was to tetracycline (54.8%), followed by streptomycin (24.2%) and sulfisoxazole (8.4%). The most common multiantimicrobial resistance patterns were to streptomycin-tetracycline (24.3%), streptomycin-sulfisoxazole-tetracycline (6.6%), and ampicillin-streptomycin-sulfisoxazole-tetracycline (3.7%). The strongest associations were observed between resistance to kanamycin and tetracycline (odds ratio = 65.7, P = 0.001) and to ampicillin and sulfisoxazole (odds ratio = 62.9, P = 0.001). Salmonella Hadar and Salmonella Heidelberg were the two most common serovars accounting for 40.4 and 13.6% of the total isolates, respectively. Eighty-one percent and 12.7% of Salmonella Hadar isolates and 62.0 and 8.1% of Salmonella Heidelberg isolates were resistant to 1 or more and three or more antimicrobials, respectively. The flock level prevalence of resistance ranged from 5.6% for trimethoprim-sulfamethoxazole to 83.3% for tetracycline. This study provides baseline information on antimicrobial susceptibility of Salmonella isolates of broiler chickens at slaughter in Alberta that can serve as a benchmark for future research.
- Published
- 2014
25. Microbiology
- Author
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Ariel Blocker, Mark S Peppler, Margaret McFall-Ngai, Philippe Normand, Francine Grimont, Eric D Spitzer, Kenneth L Rosenthal, David Sibley, Bernard Labedan, Patrick Forterre, Scott Gold, Mariola Garcia-Pedrajas, Alfredo D Martı́nez-Espinoza, John Duick, Sricharan Bandhakavi, Jeff Errington, and Andrea Feucht
- Subjects
Microbiology (medical) ,Infectious Diseases ,Microbiology - Published
- 2001
26. Evolution of Lactate Dehydrogenase-A Homologs of Barracuda Fishes (Genus Sphyraena) from Different Thermal Environments: Differences in Kinetic Properties and Thermal Stability Are Due to Amino Acid Substitutions Outside the Active Site
- Author
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George N. Somero, Margaret McFall-Ngai, and Linda Z. Holland
- Subjects
Protein Denaturation ,Lactate dehydrogenase A ,Molecular Sequence Data ,Peptide ,Peptide Mapping ,Polymerase Chain Reaction ,Biochemistry ,Cofactor ,Genus ,Oxidoreductase ,Enzyme Stability ,Barracuda ,Animals ,Amino Acid Sequence ,Muscle, Skeletal ,education ,chemistry.chemical_classification ,education.field_of_study ,Binding Sites ,Base Sequence ,L-Lactate Dehydrogenase ,Sequence Homology, Amino Acid ,biology ,Fishes ,Temperature ,Genetic Variation ,Active site ,biology.organism_classification ,Biological Evolution ,Recombinant Proteins ,Amino acid ,Isoenzymes ,Kinetics ,chemistry ,Dogfish ,Mutagenesis, Site-Directed ,biology.protein ,Thermodynamics ,Cattle ,Chickens - Abstract
Orthologous homologs of lactate dehydrogenase-A (LDH-A) (EC 1.1.1.27; NAD+:lactate oxidoreductase) of six barracuda species (genus Sphyraena) display differences in Michaelis-Menten constants (apparent Km) for substrate (pyruvate) and cofactor (NADH) that reflect evolution at different habitat temperatures. Significant increases in Km with increasing measurement temperature occur for all homologs, yet Km at normal body temperatures is similar among species because of the inverse relationship between adaptation temperature and Km. Thermal stabilities of the homologs also differ. To determine the amino acid substitutions responsible for differences in Km and thermal stability, peptide mapping of the LDH-As of all six species was first performed. Then, the amino acid sequences of the three homologs having the most similar peptide maps, those of the north temperate species, S. argentea, the subtropical species, S. lucasana, and the south temperate species, S. idiastes, were deduced from the respective cDNA sequences. At most, there were four amino acid substitutions between any pair of species, none of which occurred in the loop or substrate binding sites of the enzymes. The sequence of LDH-A from S. lucasana differs from that of S. idiastes only at position 8. The homolog of S. argentea differs from the other two sequences at positions 8, 61, 68, and 223. We used a full-length cDNA clone of LDH-A of S. lucasana to test, by site-directed mutagenesis, the importance of these sequence changes in establishing the observed differences in kinetics and thermal stability. Differences in sequence at sites 61 and/or 68 appear to account for the differences in Km between the LDH-As of S. argentea and S. lucasana. Differences at position 8 appear to account for the difference in thermal stability between the homologs of S. argentea and S. lucasana. Evolutionary adaptation of proteins to temperature thus may be achieved by minor changes in sequence at locations outside of active sites, and these changes may independently affect kinetic properties and thermal stabilities.
- Published
- 1997
27. Comparison of bacterial culture, polymerase chain reaction, and a mix-enzyme-linked immunosorbent assay for the detection of Salmonella status in grow-to-finish pigs in western Canada with a Bayesian approach
- Author
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Wendy, Wilkins, Cheryl, Waldner, Andrijana, Rajić, Margaret, McFall, Eva, Chow, and Anne, Muckle
- Subjects
Swine Diseases ,Bacteriological Techniques ,Canada ,Feces ,Salmonella Infections, Animal ,Swine ,Short Communications ,Animals ,Enzyme-Linked Immunosorbent Assay ,Real-Time Polymerase Chain Reaction ,Sensitivity and Specificity - Abstract
Among grow-to-finish pigs from 10 herds in Alberta and Saskatchewan, 23 (16%) of 144 fecal samples were culture-positive and 40 (28%) of 144 pigs were seropositive for Salmonella. With a Bayesian model specifying dependence between the 2 tests, the sensitivity (Se) of culture and real-time polymerase chain reaction (RT-PCR) was 79% to 86%, depending on the cut-off value for the enzyme-linked immunosorbent assay (ELISA). Culture specificity (Sp) was assumed to be 100%; RT-PCR Sp was found to be 94%. The ELISA Se was 76% and 51% at optical density cut-off values ≥ 20% and ≥ 40%, respectively; the Sp was 94% at each cut-off value. The model showed some sensitivity to ELISA prior information, the ELISA Se being approximately 8% lower when informative prior information was specified in the model. When there was no adjustment for dependence between culture and RT-PCR, the posterior estimates for both culture and RT-PCR Se were 11% higher than with the conditional-dependence model and had considerably narrower probability intervals, which suggests that correlation between culture and PCR is important and should be adjusted for in future studies.
- Published
- 2010
28. Evaluation of associations between feed withdrawal and other management factors with Salmonella contamination of broiler chickens at slaughter in Alberta
- Author
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Rebecca Irwin, Gary Gensler, Robin King, Margaret McFall, A. Senthilselvan, and C. Mainali
- Subjects
Serotype ,Salmonella ,animal structures ,Time Factors ,Animal feed ,animal diseases ,Transport time ,Food Contamination ,Transportation ,Biology ,medicine.disease_cause ,digestive system ,Microbiology ,Alberta ,Crop ,Animal science ,Risk Factors ,medicine ,Prevalence ,Animals ,Humans ,Animal Husbandry ,Cecum ,Poultry Diseases ,Skin ,Salmonella Infections, Animal ,fungi ,Broiler ,food and beverages ,Contamination ,Animal Feed ,Crop, Avian ,Flock ,Food Deprivation ,Chickens ,Abattoirs ,Food Science - Abstract
Salmonellosis is one of the most common bacterial foodborne diseases of public health concern in industrialized countries. Poultry products are considered an important source of Salmonella-related foodborne disease in humans. This study was undertaken to evaluate the relationship between various management factors including feed withdrawal and transportation time with Salmonella contamination in crops, ceca, and carcasses of broiler chickens at slaughter in Alberta. Using a two-stage sampling procedure, 30 matched crop and cecal samples before evisceration and an additional 30 neck skin samples after final wash of broiler chickens were collected at slaughter. A questionnaire was administered at the time of sampling to collect information on flock management risk factors. Cecal contents were individually screened with Salmonella-specific real-time PCR to detect positive flocks, and all cecal, crop, and neck skin samples from positive flocks were processed further for Salmonella isolation and characterization. The flock prevalence of Salmonella was 57.1% and within-flock prevalence of Salmonella for positive flocks was 17.2, 8.1, and 53.9% for ceca, crops, and neck skins, respectively. Salmonella Hadar was the most common serovar identified from crops, ceca, and neck skins of broiler chickens tested. Longer transport (P = 0.04 for neck skins) and waiting time in-plant (P = 0.04 for crops, P = 0.03 for ceca) were identified as important risk factors for Salmonella contamination of broiler chickens at slaughter. Salmonella contamination of broiler chickens could potentially be minimized by reducing waiting time in-plant for flocks with longer transport time.
- Published
- 2009
29. Comparison of bacterial culture, PCR and a mix-ELISA for the detection of Salmonella status in nursery and grow-to-finish pigs in Western Canada using a Bayesian approach
- Author
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Andrijana Rajić, Margaret McFall, Cheryl L. Waldner, Wendy Wilkins, Anne Muckle, Eva Y.W. Chow, and Raúl C. Mainar-Jaime
- Subjects
Salmonella ,Veterinary medicine ,Microbiological culture ,business.industry ,medicine ,Biology ,medicine.disease_cause ,business ,Biotechnology - Published
- 2009
30. Distribution of Salmonella serovars in various pig production categories and risk factors for shedding in ten farrow-to-finish swine farms in western Canada
- Author
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Wendy Wilkins, Anne Muckle, Eva Y.W. Chow, Andrijana Rajić, Leigh B Rosengren, Cheryl L. Waldner, and Margaret McFall
- Subjects
Serotype ,Salmonella ,Veterinary medicine ,business.industry ,medicine ,Distribution (economics) ,Production (economics) ,medicine.disease_cause ,business - Published
- 2009
31. Associations among antimicrobial use and antimicrobial resistance of Salmonella spp. isolates from 60 Alberta finishing swine farms
- Author
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Csaba Varga, Andrijana Rajić, Richard J. Reid-Smith, Margaret McFall, and Scott A. McEwen
- Subjects
Salmonella ,Veterinary medicine ,medicine.drug_class ,Swine ,Drug resistance ,Microbial Sensitivity Tests ,Biology ,medicine.disease_cause ,Applied Microbiology and Biotechnology ,Microbiology ,Macrolide Antibiotics ,Alberta ,Antibiotic resistance ,Ampicillin ,Drug Resistance, Multiple, Bacterial ,Surveys and Questionnaires ,Drug Resistance, Bacterial ,medicine ,Animals ,Humans ,Swine Diseases ,Salmonella Infections, Animal ,Dose-Response Relationship, Drug ,Antimicrobial ,Drug Utilization ,Anti-Bacterial Agents ,Penicillin ,Logistic Models ,Streptomycin ,Consumer Product Safety ,Food Microbiology ,Animal Science and Zoology ,Food Science ,medicine.drug - Abstract
The study objectives were to identify potential associations between reported antimicrobial use (AMU) practices and antimicrobial resistance (AMR) of fecal and environmental Salmonella spp. isolates (n = 322 isolates) recovered from 60 Alberta finishing swine farms, and to estimate the amount of pen and farm level variation in AMR. The AMU data were collected through a questionnaire. Separate multilevel logistic regression models were built for six antimicrobials with prevalence of resistanceor=5% using the Generalized Linear Latent and Mixed Model (GLLAMM) procedure. In-feed use of tylosin in finishers was associated with increased odds of resistance in Salmonella isolates to ampicillin (OR = 61.56), streptomycin (OR = 11.70), and multiple antimicrobials (OR = 4.90). Injectable penicillin use in growers was associated with decreased odds of resistance in Salmonella isolates to streptomycin (OR = 0.06), kanamycin (OR = 0.03), and multiple antimicrobials (OR = 0.12). Injectable penicillin use in finishers was associated with decreased odds of resistance in Salmonella isolates to ampicillin (OR = 0.007) and chloramphenicol (OR = 0.04). Overall, these results indicate that AMU in pig production is inconsistently associated with AMR in Salmonella from finishing swine. Variation in AMR prevalence of Salmonella isolates of swine was moderate to high at pen and farm levels for most antimicrobials suggesting that interventions at the pen and farm levels might be beneficial in reducing the emergence of AMR Salmonella in swine populations.
- Published
- 2008
32. Host-microbe symbiosis: the squid-Vibrio association--a naturally occurring, experimental model of animal/bacterial partnerships
- Author
-
Margaret, McFall-Ngai
- Subjects
Luminescence ,Host-Pathogen Interactions ,Decapodiformes ,Animals ,Symbiosis ,Models, Biological ,Vibrio - Abstract
Many, if not most, animals have specific symbiotic relationships with bacterial partners. Recent studies suggest that vertebrates create alliances with highly complex consortia of hundreds to thousands of prokaryotic phylotypes. In contrast, invertebrates often have binary associations, i.e., relationships with a population of a single bacterial species. In this chapter, the association between the Hawaiian sepiolid squid Euprymna scolopes and the marine luminous bacterium Vibrio fisheri is highlighted. This symbiosis offers a relatively simple, yet naturally occurring, association that can be experimentally manipulated. Studies of this system are providing insight into the precise mechanisms by which a beneficial animal-bacterial symbiosis can be established and maintained.
- Published
- 2008
33. Are biologists in 'future shock'? Symbiosis integrates biology across domains
- Author
-
Margaret, McFall-Ngai
- Subjects
Evolution, Molecular ,Systems Biology ,Symbiosis - Abstract
The study of symbiosis is quintessential systems biology. It integrates not only all levels of biological analysis--from molecular to ecological--but also the study of the interplay between organisms in the three domains of life. The development of this field is still in its early stages, but so far, the findings promise to revolutionize the way we view the biotic world. This Essay outlines some of the challenges facing the field and the implications of its development for all of biology.
- Published
- 2008
34. Distribution of Salmonella serovars in breeding, nursery, and grow-to-finish pigs, and risk factors for shedding in ten farrow-to-finish swine farms in Alberta and Saskatchewan
- Author
-
Wendy, Wilkins, Andrijana, Rajić, Cheryl, Waldner, Margaret, McFall, Eva, Chow, Anne, Muckle, and Leigh, Rosengren
- Subjects
Male ,Swine Diseases ,Salmonella Infections, Animal ,Swine ,Agriculture ,Animal Feed ,Housing, Animal ,Saskatchewan ,Article ,Alberta ,Feces ,fluids and secretions ,Risk Factors ,Salmonella ,Animals ,Female ,Animal Husbandry - Abstract
The study objectives were to investigate Salmonella prevalence, serovar distribution, and risk factors for shedding in 10 purposively selected farrow-to-finish farms in Saskatchewan and Alberta. Pooled fecal samples from the breeding and grow-finish phases and individual fecal samples from breeding, nursery, and grow-finish pigs were cultured for Salmonella; serotyping of isolates was performed. Pig and pen characteristics were recorded for each pig and pen sampled.Overall, 407/1143 (36%) of samples were Salmonella positive; within-farm prevalence ranged from 1% to 79%. Sows, nursery, and grow-finish pigs accounted for 43%, 29%, and 28% of positive samples, respectively. More Salmonella were detected in pooled pen than individual pig samples (P0.001). Among 418 Salmonella isolates, there were 19 distinct serovars; the most common were S. Derby (28.5%), S. Typhimurium, var. Copenhagen (19.1%), S. Putten (11.8%), S. Infantis (6.8%), and S. Mbandaka (6.1%). Sows were more likely to shed Salmonella than nursery or grow-finisher (OR 2.9, P0.001) pigs. Pelleted feed (OR 8.2, P0.001) and nose-to-nose pig contact through pens (OR 2.2, P = 0.005) were associated with increased Salmonella prevalence. Significant differences in serovar distribution were detected among production phases. The use of pooled pen samples is recommended as a more efficient means for accurate evaluation of Salmonella status in different phases of pig production. The breeding herd might be an important source of Salmonella persistence within farrow-to-finish farms and should be targeted in control efforts. The latter might also apply to the use of pelleted feed, which remains the most consistently reported significant risk factor for Salmonella shedding in pigs.
- Published
- 2008
35. Associations between reported on-farm antimicrobial use practices and observed antimicrobial resistance in generic fecal Escherichia coli isolated from Alberta finishing swine farms
- Author
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Scott A. McEwen, Andrijana Rajić, Csaba Varga, Richard J. Reid-Smith, Anne E. Deckert, Margaret McFall, and Sylvia Checkley
- Subjects
Chlortetracycline ,Veterinary medicine ,medicine.drug_class ,Swine ,Antibiotics ,Drug resistance ,Microbial Sensitivity Tests ,Biology ,Models, Biological ,Microbiology ,Alberta ,Feces ,Antibiotic resistance ,Food Animals ,Ampicillin ,Surveys and Questionnaires ,Drug Resistance, Bacterial ,medicine ,Escherichia coli ,Animals ,Poisson Distribution ,Swine Diseases ,Antiinfective agent ,Antimicrobial ,Anti-Bacterial Agents ,Multiple drug resistance ,Cross-Sectional Studies ,Regression Analysis ,Animal Science and Zoology ,medicine.drug - Abstract
Multilevel random intercept logistic and Poisson regression were used to model associations between various antimicrobial use practices and resistance to individual and multiple antimicrobials among generic fecal Escherichia coli isolated from Alberta finishing swine. In-feed antimicrobial use in finishers was significantly associated with increased risk of resistance to ampicillin, chloramphenicol, streptomycin, and sulfisoxazole in generic E. coli isolates. Chlortetracycline use in grower rations was associated with ampicillin and tetracycline resistance. Use of in-feed antimicrobials in finishers was significantly associated with increased risk of resistance of generic E. coli to multiple antimicrobials. The study findings suggest that certain farm-level interventions related to antimicrobial use might be beneficial in reducing development and emergence of antimicrobial resistance in swine populations.
- Published
- 2007
36. Adaptive immunity: care for the community
- Author
-
Margaret, McFall-Ngai
- Subjects
Bacteria ,Vertebrates ,Models, Immunological ,Animals ,Humans ,Symbiosis ,Biological Evolution ,Invertebrates ,Immunity, Innate - Published
- 2007
37. Antimicrobial resistance in fecal generic Escherichia coli in 90 Alberta swine finishing farms: prevalence and risk factors for resistance
- Author
-
S. A. McEwen, Brent P. Avery, Csaba Varga, Margaret McFall, Sylvia Checkley, Anne E. Deckert, Richard J. Reid-Smith, and Andrijana Rajić
- Subjects
Veterinary medicine ,Antibiotic resistance ,Sulfamethoxazole ,Clavulanic acid ,Ampicillin ,medicine ,Cefoxitin ,Amoxicillin ,Biology ,Antimicrobial ,Trimethoprim ,medicine.drug ,Microbiology - Abstract
gentamicin (1 .1 %), amoxicillin/clavulanic acid (0.7 %), and cefoxitin (0.7 %). Higher frequencies of resistance were observed for tetracycline (78 .9%), sulfisoxazole (49.9%), streptomycin (49.6 %), ampicillin (30 .6%), chloramphenicol (17 .62%), kanamycin (10%), and trimethoprim/sulfamethoxazole (6 .4 %). Most of the aforementioned antimicrobials are members of drug classes frequently used in veterinary medicine. Therefore, both judicious antimicrobial selection and use is needed when treating animals to preserve the ir efficacy. The most common multidrug-resistant patterns (resistance to ~ 2 antimicrobials} were streptomycin-tetracycline (9.38% ), streptomycin-sulfisoxazole-tetracycline (6.20% ), and ampicillin-streptomycin-sulfisoxazole-tetracycline (6.15% ). More clustering (less variation) in AMR was observed at the farm visit than the farm level indicating that sampling more farms with longer periods of time between farm visits might be required for better understanding of shifts in AMR over time. Risk factor analysis on the potential associations between certain on -farm AMU practices and observed AMR has been initiated and the results will be presented at the Symposium.
- Published
- 2007
38. Prevalence and relatedness of Salmoenlla spp in a Canadian abattori
- Author
-
Julia Keenliside, Gary Gensler, Robin King, Margaret McFall, and Laki Goonewardene
- Subjects
Serotype ,Veterinary medicine ,Salmonella ,animal diseases ,medicine.medical_treatment ,Pulsenet ,food and beverages ,Contamination ,Biology ,medicine.disease_cause ,Cecum ,medicine.anatomical_structure ,Pulsed-field gel electrophoresis ,medicine ,Evisceration (ophthalmology) ,Feces - Abstract
The prevalence of Salmonella contamination was assessed at five points in a Canadian pork slaughter plant. In the cooler only 0.5% (2/429) carcasses were positive, even though Salmonella were detected in 51.3% of all cecal samples and in the cecum of at least one pig in 91.5% (43/47) lots tested. Hogs held overnight in lairage were significantly more likely to have positive cecal samples. Salmonella was isolated at least once from the truck, holding pen or cecum of hogs from all 31 producers. Four serotypes comprised 70.3% of 299 isolates: Bovismorbificans, Derby, Brandenburg and Agona. PFGE showed several Salmonella strains were identical between fecal samples and carcass swabs. Many strains were different, suggesting resident bacteria or cross contamination during processing may be important in this plant. Processing interventions appear to be successfully minimizing carcass contamination in this plant. Introduction Salmonella is considered the most important food-borne pathogen from pork. Markets are requiring evidence of Salmonella control both during the production of hogs as well as pork processing. The epidemiology of Salmonella contamination is complex and not well understood. Determining the baseline prevalence of Salmonella at several steps in the pork production chain is a first step in developing a control program. Rates of Salmonella contamination on pork carcasses have been shown to vary widely between individual plants in Canada (Quessy et al., 2004). Differences in infection status of incoming hogs and different procedures in each plant play a role in carcass contamination rates. It has been reported that essentially all Salmonella spp. on pork carcasses leaving the kill floor in a slaughter plant arrive in or on the pig (Berends et al., 1997). Hogs from some farms may be chronically infected with high levels of Salmonella spp, while others may rarely be infected (Rajic et al., 2001, Berends et al., 1996). There is a reported positive correlation between the number of animals that carry Salmonella spp. in their feces and the number of contaminated carcasses (Morgan et al., 1987). Cross contamination and infection of animals can occur during lairage, making the relationship between on-farm infection status and carcass contamination less clear. Negative hogs can become infected with Salmonella within a few hours in a contaminated lairage pen. Increasing lairage time has been reported to increase infection and carcass contamination rates (Hurd et al., 2001, Morgan et al., 1997) Lairage and transport have been identified as interventionpoints where carcass contamination rates can be easily reduced (Hurd et al., 2002, Berends et al., 1996). Some authors indicate that the most cost effective place to intervene may be during processing (Berends et al., 1996). Onfarm controls have also been suggested as effective. In order to identify effective intervention points, the sources of contamination must be identified. Pulsed-field gel electrophoresis (PFGE) is one method that may be used to determine genetic relatedness of strains and sources of contamination. The objectives of this study were to determine the prevalence of Salmonella at five steps in the production chain (truck, lairage pen, cecum, carcass before evisceration, carcass in cooler); to describe Salmonella serovar diversity and relatedness at each step; and to identify risk factors for contamination. This processor would like to determine which steps are the most effective in controlling carcass contamination, and whether to focus control efforts on the farm or at the plant. Materials and Methods Hogs were purposively selected to represent the entire slaughter population based on farm of origin, duration of lairage (length of time the hog is rested before slaughter), lot size, and time of slaughter. A lot was defined as a group of hogs from one farm that were shipped together. Nine hogs were systematically selected from each targeted lot. Lots were not mixed during transport, lairage or processing. Sampling was done over three different seasons. Samples consisted of fecal samples from the truck (TF) and holding pens after lairage (HP), cecal contents (CS); and carcass swabs before O R A L P R E S E N T A T IO N S 39 SafePork 2005 evisceration (BE) and in the chilling cooler (CL). TF and HP samples consisted of 5 individual droppings combined into one 25 g sample. The side of the carcass swabbed was alternated between animals. Carcasses were swabbed following the USDA protocol (USDA, 1996) with one modification; the order of swabbing was belly, jowls then ham. Samples were transported in coolers and tested the following day. The entire swab or 10 g fecal/cecal material was enriched in buffered peptone water for 24 hours. 1 mL of this broth was transferred to tetrathionate broth (TB) and 0.1 mL to Rappaport-Vassiliadis (RVB) broth. The TB was incubated at 35 °C and RV at 42 °C for 24 hours. 150 μL of TB and RVB were combined and screened for Salmonella with real-time PCR (R-PCR). R-PCR positive samples were culturally confirmed and three isolates per sample were frozen. One isolate from each CS sample and all three isolates from CL, BE, TF and HP samples were analyzed by pulsed-field gel electrophoresis (PFGE). PFGE was performed using the PulseNet method (CDC, Atlanta, GA). Representative strains from each PFGE profile were sent to the Public Health Agency of Canada laboratory for serotyping. Results Samples were taken from 47 different lots representing 31 different farms. Salmonella was isolated at least once from the truck, holding pen or cecum of hogs from all 31 producers. Thirty-four of the 47 lots tested were held overnight in lairage before slaughter, which is representative of the typical kill at this plant where 75% of hogs are held overnight. There were significantly more positive fecal samples from the pen floor after lairage (82.9%) than from the truck floor upon arrival (40.5%) (p
- Published
- 2005
39. Estimation of sensitivity and specificty of culture and Danish-mix ELISA for detection of Salmonella in swine using Bayesian methods
- Author
-
A. Muckle, Wendy Wilkins, Margaret McFall, Cheryl L. Waldner, Eva Y.W. Chow, and A. Rajic
- Subjects
Salmonella ,Statistics ,Bayesian probability ,medicine ,Sensitivity (control systems) ,medicine.disease_cause ,Mathematics - Published
- 2005
40. Antimicrobial resistance of Salmonella isolated from finishing swine and the environment of 60 Alberta swine farms
- Author
-
Cornelius Poppe, Ken Manninen, Catherine E. Dewey, Andrijana Rajić, Margaret McFall, Scott A. McEwen, Anne E. Deckert, and Richard J. Reid-Smith
- Subjects
Salmonella ,Veterinary medicine ,Swine ,Colony Count, Microbial ,Microbial Sensitivity Tests ,Biology ,medicine.disease_cause ,Apramycin ,Microbiology ,Alberta ,Feces ,Antibiotic resistance ,Clavulanic acid ,Drug Resistance, Multiple, Bacterial ,medicine ,Animals ,Swine Diseases ,Salmonella Infections, Animal ,General Veterinary ,Sulfamethoxazole ,General Medicine ,biochemical phenomena, metabolism, and nutrition ,Trimethoprim ,Anti-Bacterial Agents ,Ciprofloxacin ,Amikacin ,medicine.drug - Abstract
The study objective was to describe and evaluate antimicrobial resistance profiles in Salmonella isolated from Alberta swine finishing farms. Salmonella isolates (n = 322) were obtained from 192 fecal and 84 environmental samples of the 60 Salmonella-positive swine finishing farms. Isolates were classified susceptible, intermediate or resistant based on NCCLS guidelines. More than half of the isolates (53.4%) were susceptible to all of the 18 antimicrobials in the testing panel. No resistance was observed to amikacin, amoxicillin/clavulanic acid, cefoxitin, ceftiofur, ceftriaxone, cephalothin, ciprofloxacin, imipenem or nalidixic acid. Less than 1% of isolates were resistant to apramycin, gentamicin and trimethoprim/sulfamethoxazole. Higher frequencies of resistance were observed for chloramphenicol (4.7%), ampicillin (7.8%), kanamycin (11.8%), sulfamethoxazole (21.1%), streptomycin (25.5%) and tetracycline (38.8%). Eleven Salmonella serovars had isolates with resistance to 3 antimicrobials. The most frequently resistant serovar was Salmonella Derby, with 27 (38.0%) isolates resistant to 3 antimicrobials, including resistance to five and six antimicrobials. An absence of resistance to cephalosporins and fluoroquniolones and a low proportion of isolates resistant to amikacin, amoxicillin/clavulanic acid, apramycin, gentamicin and trimethoprim/sulfamethoxazole are encouraging findings from public health and animal health perspectives. Frequent resistance observed for ampicillin, kanamycin, sulfamethoxazole, streptomycin and tetracycline, antimicrobials commonly used in veterinary medicine for decades, indicates an urgent need to utilize these antimicrobials more prudently if their benefits are to be preserved. Crown Copyright # 2004 Published by Elsevier B.V. All rights reserved.
- Published
- 2004
41. Microbiology. We get by with a little help from our (little) friends
- Author
-
Edward, Ruby, Brian, Henderson, and Margaret, McFall-Ngai
- Subjects
Bacteria ,Virulence Factors ,Immune System ,Vertebrates ,Animals ,Humans ,Bacterial Infections ,Bacterial Physiological Phenomena ,Biological Evolution ,Invertebrates ,Models, Biological ,Ecosystem - Published
- 2004
42. Prevalence of Salmonella in dairy herds in Alberta
- Author
-
Ole, Sorensen, Margaret, McFall, and Ken, Manninen
- Subjects
Salmonella Infections, Animal ,Cattle Diseases ,Scientific ,Microbial Sensitivity Tests ,Alberta ,Electrophoresis, Gel, Pulsed-Field ,Salmonella ,Drug Resistance, Bacterial ,Prevalence ,Animals ,Cattle ,Female ,Serotyping ,Bacteriophage Typing ,Phylogeny - Abstract
Fifty dairy herds in Alberta were tested for the presence of Salmonella. Four (8%) dairy herds had at least 1 cow shedding Salmonella. Different isolates were identified by serotyping, phage typing, and antibiotic resistance patterns. Pulsed-field gel electrophoresis patterns were determined for unique isolates.
- Published
- 2003
43. Reported antimicrobial use and Salmonella resistance on 90 Alberta swine farms
- Author
-
Andrijana Rajić, Anne Deckert, Ken Manninen, Richard Reid-Smith, Margaret McFall, Cate Dewey, and Scott A. McEwen
- Subjects
Veterinary medicine ,Salmonella ,Nalidixic acid ,animal diseases ,Biology ,medicine.disease_cause ,Apramycin ,Lincomycin ,chemistry.chemical_compound ,chemistry ,Amikacin ,Clavulanic acid ,medicine ,Carbadox ,Ceftiofur ,medicine.drug - Abstract
The study objectives were to describe antimicrobial use (AMU) and Salmonella resistance on 90 Alberta swine farms. The vast majority of antimicrobials were used in-feed. In weaners, in-feed use did not vary among farms, suggesting heavy reliance on in-feed antimicrobials. For grow-to-finish production phases, most farms reported heavy reliance on in-feed antimicrobials, but 6 and 14 farms did not report any in-feed AMU in growers and finishers, respectively. The tetracycline-sulphametazinepenicillin combination and carbadox were the most common antimicrobials added to the weaner rations, while tylosin and lincomycin were the most common antimicrobials added to grower and finisher rations. No resistance was observed to nalidixic acid, ciprofloxacin, amikacin and ceftriaxone. A low frequency of resistance (
- Published
- 2003
44. Salmonella Muenster infection in a dairy herd
- Author
-
Brian R, Radke, Margaret, McFall, and Steve M, Radostits
- Subjects
Diarrhea ,Salmonella Infections, Animal ,animal diseases ,food and beverages ,Cattle Diseases ,Scientific ,Abortion, Veterinary ,DNA Fingerprinting ,Feces ,Milk ,Pregnancy ,Risk Factors ,Salmonella ,Zoonoses ,Prevalence ,Animals ,Humans ,Cattle ,Female ,Longitudinal Studies ,Seasons ,Pregnancy Complications, Infectious ,Serotyping ,Retrospective Studies - Abstract
The overall purpose of this study was to provide information on animal and occupational health associated with the infection of a dairy herd with Salmonella Muenster that would be useful in the management of dairy herds so infected. This retrospective, longitudinal report records a 2-year infection of a 140-cow dairy herd with S. Muenster, which was likely introduced by additions to the herd. Six cows aborted or had diarrhea due to salmonellosis in the last trimester of pregnancy. Additions to the herd and the presence of animals that had not received an Escherichia coli bacterin-toxoid were risk factors for salmonellosis. One neonate died, and 24 of 36 calves born between November 1998 and May 1999 had diarrhea by 1 mo of age. Initially, over 60% of the cows were fecal positive; within 6 months, all cows but 1 had become infected. The intermittent shedding of the organism and the eventual zero prevalence highlight the inappropriateness of extensive culling as an eradication strategy. Cultures of the bulk-tank milk filters were more sensitive than cultures of the bulk-tank milk samples at detecting S. Muenster. Two months after the index case, S. Muenster was cultured from the milk of 7.8% of the cows. Positive fecal or milk cultures were not associated with impaired health or production. The herd's milk was a zoonotic risk, but contact with infected animals was not. The organism spread easily between operations, likely via manure-contaminated clothing and footwear.
- Published
- 2002
45. Salmonella spp. shedding by alberta beef cattle and the detection of Salmonella spp. in ground beef
- Author
-
Margaret McFALL, Gerald W. Ollis, Ken Manninen, Ole Sorensen, Gary Gensler, and Joyce Van Donkersgoed
- Subjects
Serotype ,Veterinary medicine ,Salmonella ,animal diseases ,Salmonella enteritidis ,Salmonella anatum ,Salmonella agona ,Microbial Sensitivity Tests ,Beef cattle ,medicine.disease_cause ,Microbiology ,Alberta ,Feces ,medicine ,Animals ,Serotyping ,biology ,food and beverages ,biology.organism_classification ,Enterobacteriaceae ,Meat Products ,Cattle ,Food Science - Abstract
Breeder cows, cattle recently arrived at feedlots, and cattle about to be shipped for slaughter were tested for Salmonella spp. No Salmonella spp. were detected in fecal samples from breeding cows. Nineteen of 1,000 (1.9%) fecal samples from recently arrived feedlot cattle were positive for Salmonella spp. compared to only 2 of 1,000 (0.2%) fecal samples taken within 2 weeks of slaughter. The positive fecal samples were collected in 5 of 50 (10%) "recent arrival" pens tested and in 1 of 50 (2%) pens tested within 2 weeks of slaughter. The serotypes isolated were Salmonella Agona, Salmonella Enteritidis, Salmonella Typhimurium DT104, and Salmonella 4,5,12:i:-. Ground beef samples purchased from retail outlets throughout Alberta were processed for Salmonella spp. Thirteen of 1,002 (1.3%) samples were positive for Salmonella spp. The serotypes isolated from ground beef were Salmonella Anatum, Salmonella Heidelberg, Salmonella Montevideo, Salmonella Typhimurium, Salmonella Typhimurium var. Copenhagen, and Salmonella Rough-O:i:1,2. The antibiotic resistance and pulsed-field electrophoresis gel macrorestriction patterns of all isolates were compared.
- Published
- 2002
46. Salmonella spp. infections in finishing swine in Alberta
- Author
-
Anne C. Muckle, John T.Y. Wu, Anne Deckert, Andrijana Rajić, Julia Keenliside, Ken Manninen, Eva Y.W. Chow, Scott A. McEwen, Cate Dewey, and Margaret McFall
- Subjects
Veterinary medicine ,Salmonella ,medicine ,Biology ,medicine.disease_cause - Published
- 2001
47. Salmonella enterica in Alberta Slaughter Hogs
- Author
-
Ken Manninen, S. Rawluk, Margaret McFall, Gerald W. Ollis, M. Schoonderwoerd, and Ole Sorensen
- Subjects
Veterinary medicine ,biology ,Salmonella enterica ,biology.organism_classification - Published
- 2001
48. Confocal microscopy of the light organ crypts in juvenile Euprymna scolopes reveals their morphological complexity and dynamic function in symbiosis.
- Author
-
Laura K. Sycuro, Edward G. Ruby, and Margaret McFall‐Ngai
- Published
- 2006
- Full Text
- View/download PDF
49. Are biologists in 'future shock'? Symbiosis integrates biology across domains.
- Author
-
McFall-Ngai M
- Subjects
- Evolution, Molecular, Symbiosis physiology, Systems Biology
- Abstract
The study of symbiosis is quintessential systems biology. It integrates not only all levels of biological analysis--from molecular to ecological--but also the study of the interplay between organisms in the three domains of life. The development of this field is still in its early stages, but so far, the findings promise to revolutionize the way we view the biotic world. This Essay outlines some of the challenges facing the field and the implications of its development for all of biology.
- Published
- 2008
- Full Text
- View/download PDF
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