Microbiology Commons^™

Forty Years Without Family: Three Novel Bacteriophages With High Similarity To Spp1 Reveal Decades Of Evolutionary Stasis Since The Isolation Of Their Famous Relative, Veronique A. Delesalle, Brianne E. Tomko, Albert C. Vill, Katherine B. Lichty, Gregory P. Krukonis

Biology Faculty Publications

SPP1, an extensively studied bacteriophage of the Gram-positive Bacillus subtilis, is a model system for the study of phage–host interactions. Despite progress in the isolation and characterization of Bacillus phages, no previously fully sequenced phages have shared more than passing genetic similarity to SPP1. Here, we describe three virulent phages very similar to SPP1; SPP1 has greater than 80% nucleotide sequence identity and shares more that 85% of its protein coding genes with these phages. This is remarkable, given more than 40 years between the isolation of SPP1 and these phages. All three phages have somewhat larger genomes and more …

Pathogenesis Of Tobacco-Associated Lung Adenocarcinoma Is Closely Coupled With Changes In The Gut And Lung Microbiomes, Casey T Finnicum, Zahraa Rahal, Maya Hassane, Warapen Treekitkarnmongkol, Ansam Sinjab, Rhiannon Morris, Yuejiang Liu, Elizabeth L Tang, Sarah Viet, Jason L Petersen, Philip L Lorenzi, Lin Tan, Joseph Petrosino, Kristi L Hoffman, Junya Fujimoto, Seyed Javad Moghaddam, Humam Kadara

Faculty, Staff and Students Publications

Microbial dysbiosis has emerged as a modulator of oncogenesis and response to therapy, particularly in lung cancer. Here, we investigate the evolution of the gut and lung microbiomes following exposure to a tobacco carcinogen. We performed 16S rRNA-Seq of fecal and lung samples collected prior to and at several timepoints following (nicotine-specific nitrosamine ketone/NNK) exposure in Gprc5a^−/− mice that were previously shown to exhibit accelerated lung adenocarcinoma (LUAD) development following NNK exposure. We found significant progressive changes in human-relevant gut and lung microbiome members (e.g., Odoribacter, Alistipes, Akkermansia, and Ruminococus) that are closely associated with …

Ridinilazole: A Novel, Narrow-Spectrum Antimicrobial Agent Targeting Clostridium (Clostridioides) Difficile, Deirdre A. Collins, Thomas V. Riley

Research outputs 2022 to 2026

Clostridium (Clostridioides) difficile infection (CDI) remains an urgent threat to patients in health systems worldwide. Recurrent CDI occurs in up to 30% of cases due to sustained dysbiosis of the gut microbiota which normally protects against CDI. Associated costs of initial and recurrent episodes of CDI impose heavy financial burdens on health systems. Vancomycin and metronidazole have been the mainstay of therapy for CDI for many years; however, these agents continue to cause significant disruption to the gut microbiota and thus carry a high risk of recurrence for CDI patients. Treatment regimens are now turning towards novel narrow spectrum antimicrobial …

Novel Technologies To Characterize And Engineer The Microbiome In Inflammatory Bowel Disease, Alba Boix-Amorós, Hilarly Monaco, Elisa Sambataro, Jose C. Clemente

Publications and Research

We present an overview of recent experimental and computational advances in technology used to characterize the microbiome, with a focus on how these developments improve our understanding of inflammatory bowel disease (IBD). Specifically, we present studies that make use of flow cytometry and metabolomics assays to provide a functional characterization of microbial communities. We also describe computational methods for strain-level resolution, temporal series, myco - biome and virome data, co-occurrence networks, and compositional data analysis. In addition, we review novel techniques to therapeutically manipulate the microbiome in IBD. We discuss the benefits and drawbacks of these technologies to increase awareness …

Phylogenetic Diversity Of Animal Oral And Gastrointestinal Viromes Useful In Surveillance Of Zoonoses, Anthony Michael Esposito, Michelle Marie Esposito, Albert Ptashnik

Publications and Research

Great emphasis has been placed on bacterial microbiomes in human and animal systems. In recent years, advances in metagenomics have allowed for the detection and characterization of more and more native viral particles also residing in these organisms. The digestive tracts of animals and humans—from the oral cavity, to the gut, to fecal excretions—have become one such area of interest. Next-generation sequencing and bioinformatic analyses have uncovered vast phylogenetic virome diversity in companion animals, such as dogs and cats, as well as farm animals and wildlife such as bats. Zoonotic and arthropod-borne illnesses remain major causes of worldwide outbreaks, as …

Frequency Of Bystander Exposure To Antibiotics For Enteropathogenic Bacteria Among Young Children In Low-Resource Settings, Elizabeth T. Rogawski Mcquade, Stephanie A. Brennhofer, Sarah E. Elwood, Timothy L. Mcmurry, Joseph A. Lewnard, Estomih R. Mduma, Sanjaya Shrestha, Najeeha Talat Iqbal, Pascal O. Bessong, Gagandeep Kang

Department of Paediatrics and Child Health

Children in low-resource settings carry enteric pathogens asymptomatically and are frequently treated with antibiotics, resulting in opportunities for pathogens to be exposed to antibiotics when not the target of treatment (i.e., bystander exposure). We quantified the frequency of bystander antibiotic exposures for enteric pathogens and estimated associations with resistance among children in eight low-resource settings. We analyzed 15,697 antibiotic courses from 1,715 children aged 0 to 2 y from the MAL-ED birth cohort. We calculated the incidence of bystander exposures and attributed exposures to respiratory and diarrheal illnesses. We associated bystander exposure with phenotypic susceptibility of E. coli isolates in …

The Cryptococcus Neoformans Flc1 Homologue Controls Calcium Homeostasis And Confers Fungal Pathogenicity In The Infected Hosts, Piotr R. Stempinski, Kristie D. Goughenour, Lukas M. Du Plooy, J. Andrew Alspaugh, Michal A. Olszewski, Lukasz Kozubowski

Open Access Publishing Fund

Cryptococcus neoformans, an opportunistic yeast pathogen, relies on a complex network of stress response pathways that allow for proliferation in the host. In Saccharomyces cerevisiae, stress responses are regulated by integral membrane proteins containing a transient receptor potential (TRP) domain, including the flavin carrier protein 1 (Flc1), which regulates calcium homeostasis and flavin transport. Here, we report that deletion of C. neoformans FLC1 results in cytosolic calcium elevation and increased nuclear content of calcineurin-dependent transcription factor Crz1, which is associated with an aberrant cell wall chitin overaccumulation observed in the flc1Δ mutant. Absence of Flc1 or inhibition …

Whole-Genome Sequencing Links Clostridium (Clostridioides) Difficile In A Single Hospital To Diverse Environmental Sources In The Community, Su-Chen Lim, Deirdre Collins, Korakrit Imwattana, Daniel R. Knight, Sicilia Perumalsamy, Natasza M.R. Hain-Saunders, Papanin Putsathit, David Speers, Thomas Riley

Research outputs 2022 to 2026

To investigate if Clostridium (Clostridioides) difficile infection (CDI), traditionally thought of as hospital-acquired, can be genomically linked to hospital or community environmental sources, and to define possible importation routes from the community to the hospital.

In 2019, C. difficile was isolated from 89/300 (29.7%) floor and 96/300 (32.0%) shoe sole samples at a tertiary hospital in Western Australia. Non-toxigenic C. difficile ribotype (RT) 010 predominated among floor (96.6%) and shoe sole (73.2%) isolates, while toxigenic RT 014/020 was most prevalent among contemporaneous clinical cases (33.0%) at the hospital. Whole-genome sequencing and high-resolution core genome single nucleotide polymorphism (cgSNP) …

Genetic Determinants Of Carotenoid Pigmentation In The Opportunistic Pathogen Mycobacterium Kansasii, Niklas Janisch

Dissertations, Theses, and Capstone Projects

Mycobacterium kansasii (Mk) is an opportunistic pulmonary pathogen causing infections, predominantly in immunocompromised people, with symptoms similar to those caused by its close relative Mycobacterium tuberculosis (Mt). In contrast to the latter, little work has been done on Mk genetics and even less on its defining characteristic of photochromogenicity, the controlled expression of carotenoid pigments in response to light exposure.

This work represents major progress in the investigation of pigmentation-related genetic factors in Mk. We report the creation of a large-scale, random transposon-insertion mutant library of Mk and its subsequent screening for mutants with an aberration in the …

Elucidation Of Gene Essentiality And Genetic Determinants Of Intrinsic P-Aminosalicylic Acid Resistance In Mycobacterium Kansasii, Keith J. Levendosky

Dissertations, Theses, and Capstone Projects

Mycobacterium kansasii (Mk) is an opportunistic pathogen capable of causing tuberculosis-like pulmonary disease in immunocompromised individuals and those with other risk factors including chronic obstructive pulmonary disease or malignancy. Mk is frequently isolated from man-made water sources where it forms resilient biofilms, posing a health risk to these susceptible individuals. Despite its medical relevance as an environmental pathogen, and a close phylogenetic relationship with the obligate pathogen Mycobacterium tuberculosis (Mtb), few studies to date have probed the molecular biology and genetics of Mk. Here, we sought to apply a transposon (Tn) mutagenesis tool to dissect …

Esculin Hydrolysis Negative And Tcda-Only Producing Strains Of Clostridium (Clostridioides) Difficile From The Environment In Western Australia, Nirajmohan Shivaperumal, Daniel R. Knight, Korakrit Imwattana, Grace O. Androga, Barbara J. Chang, Thomas V. Riley

Research outputs 2022 to 2026

Background and Aims: Clostridium (Clostridiodes) difficile clade 3 ribotype (RT) 023 strains that fail to produce black colonies on bioMérieux ChromID agar have been reported, as well as variant strains of C. difficile that produce only toxin A. We have recently isolated strains of C. difficile from the environment in Western Australia (WA) with similar characteristics. The objective of this study was to characterize these strains. It was hypothesized that a putative β-glucosidase gene was lacking in these strains of C. difficile, including RT 023, leading to white colonies. Methods and Results: A total of 17 environmental isolates of C. …

System Design For The Quantification Of Microbial Motility In Extreme Environments, Megan Marie Dubay

Dissertations and Theses

Motility of microorganisms is understudied but provides useful insights into their behavior. Organisms' ability to move autonomously changes how they interact with their environment--finding nutrients, interacting with other organisms, and avoiding unfavorable conditions. Understanding motility features can also be used to identify specific species, such as the identification of Vibrio cholerae in human samples. Motility might also be used as evidence of life existing in even the most extreme environments on Earth, and possibly beyond. Specialized microscopy systems can be required to examine the motility of microorganisms due to the nature of the environments to which the instruments are exposed. …

Phage Resistance Accompanies Reduced Fitness Of Uropathogenic Escherichia Coli In The Urinary Environment, Jacob J Zulk, Justin R Clark, Samantha Ottinger, Mallory B Ballard, Marlyd E Mejia, Vicki Mercado-Evans, Emmaline R Heckmann, Belkys C Sanchez, Barbara W Trautner, Anthony W Maresso, Kathryn A Patras

Faculty, Staff and Students Publications

Urinary tract infection (UTI) is among the most common infections treated worldwide each year and is caused primarily by uropathogenic Escherichia coli (UPEC). Rising rates of antibiotic resistance among uropathogens have spurred a consideration of alternative treatment strategies, such as bacteriophage (phage) therapy; however, phage-bacterial interactions within the urinary environment are poorly defined. Here, we assess the activity of two phages, namely, HP3 and ES17, against clinical UPEC isolates using in vitro and in vivo models of UTI. In both bacteriologic medium and pooled human urine, we identified phage resistance arising within the first 6 to 8 h of coincubation. …

Integrated Relationship Of Nasopharyngeal Airway Host Response And Microbiome Associates With Bronchiolitis Severity, Michimasa Fujiogi, Yoshihiko Raita, Marcos Pérez-Losada, Robert J Freishtat, Juan C Celedón, Jonathan M Mansbach, Pedro A Piedra, Zhaozhong Zhu, Carlos A Camargo, Kohei Hasegawa

Faculty, Staff and Students Publications

Bronchiolitis is a leading cause of infant hospitalizations but its immunopathology remains poorly understood. Here we present data from 244 infants hospitalized with bronchiolitis in a multicenter prospective study, assessing the host response (transcriptome), microbial composition, and microbial function (metatranscriptome) in the nasopharyngeal airway, and associate them with disease severity. We investigate individual associations with disease severity identify host response, microbial taxonomical, and microbial functional modules by network analyses. We also determine the integrated relationship of these modules with severity. Several modules are significantly associated with risks of positive pressure ventilation use, including the host-type I interferon, neutrophil/interleukin-1, T cell …

Redundancy And Developmental Coordination In Myxococcus Xanthus: Insights From The Phenome, Jessica A. Comstock

Dissertations - ALL

Genotype-to-phenotype mapping can typically involve disrupting the function of a gene and observing the impact of mutation on phenotype. While this can be a powerful tool for uncovering gene function, complicating factors such as influences between genes and the environment, epistatic interactions with other genes, and genetic redundancy could all potentially mask the phenotype of a mutation such that functional inferences cannot be made. On the level of the single gene, this may not be particularly informative, but it is possible that studying phenotype in this way at a genome scale might allow for the observation of patterns between genes …

Nla28 Activator Modulates Σ54-Dependent Gene Regulation In Myxococcus Xanthus, Muqing Ma

Dissertations - ALL

The complex life cycle of Myxococcus xanthus makes it a model organism for studying multicellular developmental processes in bacteria. In response to environmental changes, M. xanthus cells collectively and dramatically adjust their morphology, physiological functions, and biosynthesis. Particularly, M. xanthus copes with starvation by producing fruiting bodies filled with dormant and stress-resistant spores. During secondary metabolism, it synthesizes polyketide (PK) and non-ribosomal peptide (NRP) natural products that are crucial sources of antibiotics. Bacteria including M. xanthus, require the alternative σ54 regulatory system to initiate the transcription of necessary genes for settling stress and completing developmental process. This dissertation introduces in …

Listeria Monocytogenes Is A Solvent Tolerant Organism Secreting A Solvent Stable Lipase: Potential Biotechnological Applications, Priyanka Priyanka Dr, Gemma K. Kinsella, Gary T. Henehan Prof, Barry J. Ryan Dr

Articles

Purpose The emerging biobased economy will require robust, adaptable, organisms for the production and processing of biomaterials as well as for bioremediation. Recently, the search for solvent tolerant organisms and solvent tolerant enzymes has intensifed. Resilient organisms secreting solvent stable lipases are of particular interest for biotechnological applications.

Methods Screening of soil samples for lipase-producing organisms was carried out on Rhodamine B plates. The most productive lipase-producing organisms were further screened for their resistance to solvents commonly used in biotechnological applications.

Results In the course of screening, one of the isolated organisms that exhibited extracellular lipaseactivity, was identifed as the …

The Roles Of Gut Microbiome And Plasma Metabolites In The Associations Between Abo Blood Groups And Insulin Homeostasis: The Microbiome And Insulin Longitudinal Evaluation Study (Miles), Ruifang Li-Gao, Kirk Grubbs, Alain G Bertoni, Kristi L Hoffman, Joseph F Petrosino, Gautam Ramesh, Martin Wu, Jerome I Rotter, Yii-Der Ida Chen, Anne M Evans, Richard J Robinson, Laura Sommerville, Dennis Mook-Kanamori, Mark O Goodarzi, Gregory A Michelotti, Patricia A Sheridan

Faculty, Staff and Students Publications

Non-O blood groups are associated with decreased insulin sensitivity and risk of type 2 diabetes. A recent study pinpointed the associations between ABO blood groups and gut microbiome, which may serve as potential mediators for the observed increased disease risks. We aimed to characterize associations between ABO haplotypes and insulin-related traits as well as potential mediating pathways. We assessed insulin homeostasis in African Americans (AAs; n = 109) and non-Hispanic whites (n = 210) from the Microbiome and Insulin Longitudinal Evaluation Study. The ABO haplotype was determined by six SNPs located in the ABO gene. Based on prior knowledge, …

Igg Antibodies To Sars-Cov-2 In Asymptomatic Blood Donors At Two Time Points In Karachi, Muhammad Hasan, Bushra Moiz, Shama Qaiser, Kiran I. Masood, Zara Ghous, Areeba Hussain, Natasha Bahadur Ali, Syed Hani Abidi, Kulsoom Ghias, Erum Khan, Zahra Hasan

Department of Pathology and Laboratory Medicine

Introduction: An estimated 1.5 million cases were reported in Pakistan until 23 March, 2022. However, SARS-CoV-2 PCR testing capacity has been limited and the incidence of COVID-19 infections is unknown. Volunteer healthy blood donors can be a control population for assessment of SARS-CoV-2 exposure in the population. We determined COVID-19 seroprevalence during the second pandemic wave in Karachi in donors without known infections or symptoms in 4 weeks prior to enrollment.
Materials and methods: We enrolled 558 healthy blood donors at the Aga Khan University Hospital between December 2020 and February 2021. ABO blood groups were determined. Serum IgG reactivity …

Behavioural Support And Nicotine Replacement Therapy For Smokeless Tobacco Cessation: Protocol For A Pilot Randomised-Controlled Multi-Country Trial, Faraz Siddiqui, Linda Bauld, Ray Croucher, Cath Jackson, Ian Kellar, Mona Kanaan, Subhash Pokhrel, Rumana Huque, Romaina Iqbal, Javaid Ahmed Khan

Community Health Sciences

Background: Smokeless tobacco (ST) is consumed globally by more than 350 million people, with approximately 85% of all users based in South and Southeast Asia. In this region, ST products are cheap and easily accessible. Evidence-based interventions to people quit ST use are lacking. This study aims to test the feasibility of conducting a future definitive trial of ST cessation, using a culturally adapted behavioural intervention, and/or nicotine replacement therapy (NRT) in three South Asian countries.
Methods: We will conduct a factorial design, randomised-controlled pilot trial in Bangladesh, India and Pakistan. Daily ST users will be recruited from primary health …

Mechanisms Of Carbapenemase-Mediated Resistance Among High-Risk Pseudomonas Aeruginosa Lineages In Peru, Isabella A. Tickler, Juan Carlos Gomez De La Torre, Luis Alvarado, Anne E. Obradovich, Fred C. Tenover

Biology Faculty Publications

Objectives: Pseudomonas aeruginosa is one of the leading causes of healthcare-associated infections globally. High-risk carbapenemase-encoding P. aeruginosa clones are disseminating in many regions. The aim of this study was to learn more about the lineages and mechanisms of resistance of P. aeruginosa circulating in Peru.

Methods: A total of 141 carbapenemase-producing isolates recovered from hospitalized and ambulatory patients in Lima were sequenced and analyzed to infer their lineages through whole-genome sequence typing (wgST) and to identify their antimicrobial resistance genes.

Results: wgST identified nine sequence types (STs); ST111 and ST357 were the most frequently encountered (44.0% and 38.3%, respectively), followed …

Consequences Of Biofilm Architecture On Vibrio Cholerae Ecology And Life History, Benjamin Ray Wucher

Dartmouth College Ph.D Dissertations

The diversity of microbes and the environments they inhabit are staggering. In many of these environments, bacteria have evolved to form sessile surface attached communities called biofilms. These biofilms have wide reaching impacts from importance in global carbon cycling, to persistent catheter infections, to biofouling and wastewater treatment. While many species of microbes form biofilms to survive in their environment, the architectures of these structures vary widely between organisms. Even though a great deal of work has been done to understand bacterial communities and their functions, little work has examined how the spatial aspects of biofilm architecture can affect the …

Microbial Dimension Of Symbiosis And Dysbiosis In Fungus–Gardening Ants, Blake S. Bringhurst

Biology Theses

With symbiotic partners, the means by which a host obtain a symbiont influence the specificity between the host and the symbiont. One such system where symbiont specificity is seen to varying degrees is with higher attine ants. Higher attine ants have symbiotic relationships with the fungal cultivar they grow and the bacterial symbionts in their microbiomes. Among the higher attines, there are two broad groups of fungi. Most ants in the genus Trachymyrmex tend to grow Clade–B fungi, which are a group of undescribed Leucocoprinus species, while leaf–cutting ants in the genera Acromyrmex and Atta tend to grow Clade–A fungi …

Complete Genome Sequences Of Two Temperate Bacillus Subtilis Phages Isolated At Tumamoc Hill Desert Laboratory, Gregory P. Krukonis, Amanda K. Kemp, Katie F. Storrie, Vivian R. Chavira, Hayden W. Lantrip, Victoria D. Perez, Desiree A. Reyes, Julian A. Truax, Rachel Loney, Veronique A. Delesalle

Biology Faculty Publications

Bacteriophages are important in structuring bacterial communities, including desert soils dominated by Bacillus species. Here, we describe two genetically similar temperate phages isolated on a Bacillus subtilis strain from soil in Tucson, Arizona. Their double-stranded DNA (dsDNA) genomes contain 98 and 102 genes, with a set of 4 genes being found in only one phage.

From The Headlines: A Textual Analysis Of Social Polarization And Discord In Times Of Pandemic Across A Century In The United States, Alexa Demarco

Undergraduate Honors Theses

Within the past century, three major pandemics have affected the United States – the Spanish Flu, AIDS, and COVID-19. Each of these pandemics has tested the capabilities of the public health sector and the social resilience of the population. Scientists have studied the viruses and implemented public health measures to limit viral transmission, but the social responses to these preventative measures proved to be difficult to predict and control. The dissonance and polarization between the public health initiatives and the response of the general public in the most recent pandemic was apparent. Was this a pattern in other pandemics? Was …

Intrinsic Cardiac Effects Of Severe Acute Respiratory Syndrome Coronavirus 2 In Coronavirus Disease 2019, Brittany Danielle Brumback

McKelvey School of Engineering Graduate Student Theses & Dissertations

Cardiac arrhythmias, particularly ventricular arrhythmias, can be life-threatening and caused by both congenital genetic mutations and acquired cardiac injury. My thesis work was originally focused on delineating the effects of genetic mutation-driven dysregulation of a protein called Hey2 in Brugada Syndrome, a complex disease characterized by a predisposition to dangerous arrhythmias originating in the right ventricular outflow tract. In response to the pandemic, my thesis work shifted toward understanding the mechanisms of cardiovascular injury in Coronavirus disease 2019 (COVID-19), which is associated with serious cardiovascular complications, including ventricular arrhythmias and sudden cardiac death as well as endothelial dysfunction and coagulopathies. …

Comparative Genomics And Virulence Studies Of Streptomyces Soil Rot And Scab Pathogen Species, Natasha Soares

LSU Doctoral Dissertations

Comparative genomic analyses were performed to gain insights into the organization and content of the genome of Streptomyces ipomoeae, the soil rot pathogen that infects sweetpotatoes. Unlike Streptomyces scab pathogens, the thaxtomin phytotoxin gene cluster (txt) in S. ipomoeae does not appear to reside within a genomic island and has diverged from its scab pathogen counterparts. Increased usage of the rare TTA codon, particularly for the txt cluster, suggests greater translational control by the bldA tRNA in S. ipomoeae. Orthologous gene searches and secondary metabolite profiling yielded ortholog groups and metabolite gene clusters that were exclusive …

Understanding Control Of Metabolite Dynamics And Heterogeneity, Christopher John Hartline

McKelvey School of Engineering Graduate Student Theses & Dissertations

Microbes live in complex and continually changing environments. Rapid shifts in nutrient availability are a common challenge for microbes, and cause changes in intracellular metabolite levels. Microbial response to dynamic environments requires coordination of multiple levels of cellular machinery including gene expression and metabolite concentrations. This coordination is achieved through metabolic control systems, which sense metabolite concentrations and direct cellular activity in response. Several reoccurring control architectures are found throughout diverse metabolic systems, which suggests underlying evolutionary advantages for using these control systems to coordinate metabolism. One common, yet understudied, control architecture is the positive feedback metabolite uptake loop, which …

Formulasi Pembawa Rizobakteri Penambat Nitrogen Dan Pelarut Fosfat, Serta Aplikasinya Di Pembibitan Kelapa Sawit Yang Diberi Komposisi Dan Dosis Amelioran Yang Berbeda, Roby Ibnu Syarifain, Mohammad Raihan Rashaun, Eka Dewi Anggrainy, Tualar Simarmata

Jurnal Kultivasi

Keberhasilan aplikasi pupuk hayati berkaitan dengan viabilitas mikroba dalam pembawa, dan aplikasinya di lapangan. Penelitian ini bertujuan mengetahui viabilitas Bakteri Penambat Nitrogen (BPN) dan Bakteri Pelarut Fosfat (BPF) pada berbagai komposisi karier, konsentrasi molase, dan aplikasinya dengan berbagai dosis serta komposisi amelioran pada pembibitan kelapa sawit. Penelitian dilaksanakan dari bulan Oktober 2019 - Mei 2020 di laboratorium dan kebun percobaan Ciparanje. Tahap pertama menggunakan Rancangan Acak Lengkap dua faktor (komposisi karier dan konsentrasi molase) dengan tiga ulangan. Tahap kedua menggunakan rancangan acak kelompok faktorial dua faktor (komposisi amelioran dan dosis aplikasi) pada pembibitan kelapa sawit sebanyak tiga ulangan. Hasil riset …

Investigating Host Defenses Of North American Salamanders Against The Recently Emerged Chytrid Pathogen, Batrachochytrium Salamandrivorans, Kenzie Pereira

Electronic Theses and Dissertations

A recently emerged chytrid fungal pathogen, Batrachochytrium salamandrivorans (Bsal) threatens salamander biodiversity. Bsal susceptibility varies between and within salamander species, but little is known about the mechanisms underlying these differences. Susceptibility is likely influenced by numerous interacting factors, but my dissertation studied the role of host immune responses.

My first aim investigated between species differences by studying the bioactive properties of salamander skin peptides against Bsal and the related pathogen, B. dendrobatidis (Bd). Skin peptides were collected from five salamander species, used for in vitro assays, and analyzed by RP-HPLC. While skin peptides from one …