Life Sciences Commons^™

A Mouse Model Of Human Tlr4 D299g/T399i Snps Reveals Mechanisms Of Altered Lps And Pathogen Responses, Katharina Richard, Kurt H. Piepenbrink, Kari Ann Shirey, Archana Gopalakrishnan, Shreeram Nallar, Daniel J. Prantner, Darren J. Perkins, Wendy Lai, Alexandra Vik, Vladimir Y. Toshchakov, Chiguang Feng, Rachel Fanaroff, Andrei E. Medvedev, Jorge C.G. Blanco, Stefanie N. Vogel

Department of Food Science and Technology: Faculty Publications

Two cosegregating single-nucleotide polymorphisms (SNPs) in human TLR4, an A896G transition at SNP rs4986790 (D299G) and a C1196T transition at SNP rs4986791 (T399I), have been associated with LPS hyporesponsiveness and differential susceptibility to many infectious or inflammatory diseases. However, many studies failed to confirm these associations, and transfection experiments resulted in conflicting conclusions about the impact of these SNPs on TLR4 signaling. Using advanced protein modeling from crystallographic data of human and murine TLR4, we identified homologous substitutions of these SNPs in murine Tlr4, engineered a knock-in strain expressing the D298G and N397I TLR4 SNPs homozygously, and characterized in vivo …

Steps In Metagenomics: Let’S Avoid Garbage In And Garbage Out, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Is metagenomics a revolution or a new fad? Metagenomics is tightly associated with the availability of next-generation sequencing in all its implementations. The key feature of these new technologies, moving beyond the Sanger-based DNA sequencing approach, is the depth of nucleotide sequencing per sample.¹ Knowing much more about a sample changes the traditional paradigms of “What is the most abundant?” or “What is the most significant?” to “What is present and potentially sig­nificant that might influence the situation and outcome?” Let’s take the case of identifying proper biomarkers of disease state in the context of chronic disease prevention. Prevention …

Metagenomics For Bacteriology, Erika Del Castillo, Jacques Izard

Department of Food Science and Technology: Faculty Publications

The study of bacteria, or bacteriology, has gone through transformative waves since its inception in the 1600s. It all started by the visualization of bacteria using light microscopy by Antonie van Leeuwenhoek, when he first described “animalcules.” Direct cellular observation then evolved into utilizing different wavelengths on novel platforms such as electron, fluorescence, and even near-infrared microscopy. Understanding the link between microbes and disease (pathogenicity) began with the ability to isolate and cultivate organisms through aseptic methodologies starting in the 1700s. These techniques became more prevalent in the following centuries with the work of famous scientists such as Louis Pasteur …

Metagenomics For Microbiology: Preface, Jacques Izard, Maria C. Rivera

Department of Food Science and Technology: Faculty Publications

It is well known that only a small fraction of extant microbial life has been identified. Metagenomics, the direct sequencing and characterization of genes and genomes present in complex microbial ecosystems (e.g., metagenomes), has revolutionized the practice of microbiology by bypassing the hurdle of pure culture isolation. Metagenomics shows promise of advancing our understanding of the diversity, function, and evolution of the uncultivated majority.

Metagenomics as a field arose in the 1990s after the application of molecular biology techniques to genomic material directly extracted from microbial assemblages present in diverse habitats, including the human body. The application of metagenomic approaches …

Promises And Prospects Of Microbiome Studies, Maria C. Rivera, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Since Anthony van Leeuwenhoek, first microscopic observations of the unseen microbiota and the more recent realization that little of the microbes in the biosphere are known, humans have developed a deep curiosity to fully understand the inner workings of the microbial realm. Our ability to characterize the complexity of microbial communities in their natural habitats has dramatically improved over the past decade thanks to advances in high-throughput methodologies. By eliminating the need to isolate and culture individual species, metagenomics approaches have removed many of the obstacles that hindered research in the ecology of mixed microbial consortia, providing valuable information about …

Characterization Of The Ecological Role Of Genes Mediating Acid Resistance In Lactobacillus Reuteri During Colonization Of The Gastrointestinal Tract, Janina A. Krumbeck, Nathan L Marsteller, Steven Frese, Daniel A. Peterson, Amanda Ramer-Tait, Robert W. Hutkins, Jens Walter

Department of Food Science and Technology: Faculty Publications

Rodent-derived strains of Lactobacillus reuteri densely colonize the forestomach of mice and possess several genes whose predicted functions constitute adaptations towards an acidic environment. The objective of this study was to systematically determine which genes of L. reuteri 100-23 contribute to tolerance towards host gastric acid secretion. Genes predicted to be involved in acid resistance were inactivated, and their contribution to survival under acidic conditions was confirmed in model gastric juice. Fitness of five mutants that showed impaired in vitro acid resistance were then compared through competition experiments in ex-germ-free mice that were either treated with omeprazole, a proton-pump inhibitor …

The Human Gut Microbiome: Ecology And Recent Evolutionary Changes, Jens Walter, Ruth Ley

Department of Food Science and Technology: Faculty Publications

The human gastrointestinal tract is divided into sections, allowing digestion and nutrient absorption in the proximal region to be separate from the vast microbial populations in the large intestine, thereby reducing conflict between host and microbes. In the distinct habitats of the gut, environmental filtering and competitive exclusion between microbes are the driving factors shaping microbial diversity, and stochastic factors during colonization history and in situ evolution are likely to introduce intersubject variability. Adaptive strategies of microbes with different niches are genomically encoded: Specialists have smaller genomes than generalists, and microbes with environmental reservoirs have large accessory genomes. A shift …

Building The Genomic Base-Layer Of The Oral “Omic” World, The Forsyth Metagenomic Support Consortium, Jacques Izard

Department of Food Science and Technology: Faculty Publications

With the shift of molecular technologies directed toward the understanding of greater biological complexity of the oral cavity, a knowledge gap was created by the lack of genomic data from the diverse oral microorganisms. To facilitate and enable the interpretation of metagenomic, transcriptomic, and proteomic data generated or soon to be generated from oral biofilms, we are providing reference genomic information from phylogenetically diverse oral bacterial isolates. This work, initiated by the National Institute of Dental and Craniofacial Research as an isolated effort, is now part of the Human Microbiome Project. The goal of this effort is the public release …

Tannerella Forsythia, A Periodontal Pathogen Entering The Genomic Era, Anne C.R. Tanner, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Several questions need to be addressed to evaluate whether Tannerella forsythia is to be considered a periodontal pathogen. T. forsythia has been detected in periodontal health and disease, so could it be a pathogen? The species was not detected in many studies despite finding other putative pathogens, so could it be important in pathogenicity? The challenges of working with T. forsythia include its fastidious and anaerobic growth requirements for cultural detection. Thus, studies associating T. forsythia with periodontal and other oral infections have used noncultural approaches (immunoassays and DNA-based assays) in addition to cultural approaches. We feel the timing of …