Mycoplasma iowae is a well-established avian pathogen that can infect and damage many sites throughout the body. One potential mediator of cellular damage by mycoplasmas is the production of H2O2 via a glycerol catabolic pathway whose genes are widespread amongst many mycoplasma species. Previous sequencing of M. iowae serovar I strain 695 revealed the presence of not only genes for H2O2 production through glycerol catabolism but also the first documented mycoplasma gene for catalase, which degrades H2O2. To test the activity of M. iowae catalase in degrading H2O2, we studied catalase activity and H2O2 accumulation by both M. iowae serovar K strain DK-CPA, whose genome we sequenced, and strains of the H2O2-producing species Mycoplasma gallisepticum engineered to produce M. iowae catalase by transformation with the M. iowae putative catalase gene, katE. H2O2-mediated virulence by M. iowae serovar K and catalase-producing M. gallisepticum transformants were also analyzed using a Caenorhabditis elegans toxicity assay, which has never previously been used in conjunction with mycoplasmas. We found that M. iowae katE encodes an active catalase that, when expressed in M. gallisepticum, reduces both the amount of H2O2 produced and the amount of damage to C. elegans in the presence of glycerol. Therefore, the correlation between the presence of glycerol catabolism genes and the use of H2O2 as a virulence factor by mycoplasmas might not be absolute.
The poultry-associated bacterium Mycoplasma iowae colonizes multiple sites in embryos, with disease or death resulting. Although M. iowae accumulates in the intestinal tract, it does not cause disease at that site, but rather only in tissues that are exposed to atmospheric O2. The activity of M. iowae catalase, encoded by katE, is capable of rapid removal of damaging H2O2 from solution, and katE confers a substantial reduction in the amount of H2O2 produced by Mycoplasma gallisepticum katE transformants in the presence of glycerol. As catalase-producing bacteria are often beneficial to hosts with inflammatory bowel disease, we explored whether M. iowae was exclusively protective against H2O2-producing bacteria in a Caenorhabditis elegans model, whether its protectiveness changed in response to O2 levels, and whether expression of genes involved in H2O2 metabolism and virulence changed in response to O2 levels. We observed that M. iowae was in fact protective against H2O2-producing Streptococcus pneumoniae, but not HCN-producing Pseudomonas aeruginosa, and that M. iowae cells grown in 1% O2 promoted survival of C. elegans to a greater extent than M. iowae cells grown in atmospheric O2. Transcript levels of an M. iowae gene encoding a homolog of Mycoplasma pneumoniae CARDS toxin were 5-fold lower in cells grown in low O2. These data suggest that reduced O2, representing the intestinal environment, triggers M. iowae to reduce its virulence capabilities, effecting a change from a pathogenic mode to a potentially beneficial one.
Immunology education has historically been delivered at the graduate level. Calls for reform in biology education and increased workforce demand for individuals trained in immunology have spurred efforts to examine immunology education at the undergraduate level. The Undergraduate Immunology Education Consortium, a newly formed international group of immunology educators representing diverse institutions, is contributing to this effort through the development of curricular resources and student learning outcomes. We have identified a set of fundamental concepts that are critical to the understanding of immunology for undergraduate students and align with the 2011 AAAS Vision and Change Report. To identify consensus among immunology educators this group distributed an initial online survey to immunology educators to evaluate the identified fundamental concepts. Following survey feedback, the concepts were revised, submitted for further evaluation by immunology educators in focus groups, and then distributed in a final survey. Analyses of the data from the initial survey demonstrated that the respondent pool represented a varied and diverse range of expertise. Although teaching experience and current role in teaching influenced the proportion of time allotted to some immunology subtopics, topics of greatest emphasis included innate immunity, adaptive immunity, host-pathogen interactions, and molecular mechanisms. An understanding of current curricular practices by immunology educators will further aid in the refinement of the fundamental concepts, their interdisciplinary use in a diverse range of undergraduate science curricula, and future collection of assessment data to analyze effective best practices.
Until recently, immunology education was primarily introduced at the graduate level. However, in the age of modern medicine, a fundamental understanding of the immune system is becoming increasingly critical. The immune system affects every organ system in the body, and entails many concepts that are critical for training students who wish to pursue health professions or research-intensive careers. In addition to medicine, ecologists and computer scientists have lately been attracted to the field to investigate problems related to ecoimmunology or for development of machine learning tools for disease modeling. The need to focus on undergraduate immunology education has been strongly recognized and advocated for in several recent publications. In response to this need, we, a newly formed task force of undergraduate immunology educators, have identified fundamental concepts that are critical to the understanding of immunology for undergraduate students. We have aligned these fundamental statements with the overarching concepts described in the AAAS report “Vision and Change in Undergraduate Biology Education: A Call to Action”, and are now gathering feedback on these guidelines from undergraduate educators at large. Establishment of these guidelines is consistent with new pedagogical practices that emphasize conceptual understanding of the subject over rote memorization and provides a framework needed to introduce students to immunology. The goal of this project is to solicit feedback from the immunology community in an effort to achieve consensus regarding the fundamental concepts in immunology that are critical for STEM-focused students to comprehend.
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