14 research outputs found
Impact of Metabolomics in Symbiosis Research
In symbiotic associations, there is a constant molecular complexity that allows establishment and maintenance of the relationship. Metabolomic profiles have enabled researchers to explain symbiotic associations in terms of their underlying molecules and interactions between the symbiotic partners. In this review, we have selected studies on symbioses as examples that have helped to explain the metabolic integration of bacterial symbionts and their hosts in an effort to understand the molecular fingerprint of animal-microbial symbioses
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Identification of a Transcriptomic Network Underlying the Wrinkly and Smooth Phenotypes of Vibrio fischeri.
Vibrio fischeri is a cosmopolitan marine bacterium that oftentimes displays different colony morphologies, switching from a smooth to a wrinkly phenotype in order to adapt to changes in the environment. This wrinkly phenotype has also been associated with increased biofilm formation, an essential characteristic for V. fischeri to adhere to substrates, to suspended debris, and within the light organs of sepiolid squids. Elevated levels of biofilm formation are correlated with increased microbial survival of exposure to environmental stressors and the ability to expand niche breadth. Since V. fischeri has a biphasic life history strategy between its free-living and symbiotic states, we were interested in whether the wrinkly morphotype demonstrated differences in its expression profile in comparison to the naturally occurring and more common smooth variant. We show that genes involved in major biochemical cascades, including those involved in protein sorting, oxidative stress, and membrane transport, play a role in the wrinkly phenotype. Interestingly, only a few unique genes are specifically involved in macromolecule biosynthesis in the wrinkly phenotype, which underlies the importance of other pathways utilized for adaptation under the conditions in which Vibrio bacteria are producing this change in phenotype. These results provide the first comprehensive analysis of the complex form of genetic activation that underlies the diversity in morphologies of V. fischeri when switching between two different colony morphotypes, each representing a unique biofilm ecotype.IMPORTANCE The wrinkly bacterial colony phenotype has been associated with increased squid host colonization in V. fischeri The significance of our research is in identifying the genetic mechanisms that are responsible for heightened biofilm formation in V. fischeri This report also advances our understanding of gene regulation in V. fischeri and brings to the forefront a number of previously overlooked genetic networks. Several loci that were identified in this study were not previously known to be associated with biofilm formation in V. fischeri
Gene-Swapping Mediates Host Specificity among Symbiotic Bacteria in a Beneficial Symbiosis
<div><p>Environmentally acquired beneficial associations are comprised of a wide variety of symbiotic species that vary both genetically and phenotypically, and therefore have differential colonization abilities, even when symbionts are of the same species. Strain variation is common among conspecific hosts, where subtle differences can lead to competitive exclusion between closely related strains. One example where symbiont specificity is observed is in the sepiolid squid-<i>Vibrio</i> mutualism, where competitive dominance exists among <i>V. fischeri</i> isolates due to subtle genetic differences between strains. Although key symbiotic loci are responsible for the establishment of this association, the genetic mechanisms that dictate strain specificity are not fully understood. We examined several symbiotic loci (<i>lux</i>-bioluminescence, <i>pil</i> = pili, and <i>msh</i>-mannose sensitive hemagglutinin) from mutualistic <i>V. fischeri</i> strains isolated from two geographically distinct squid host species (<i>Euprymna tasmanica</i>-Australia and <i>E. scolopes</i>-Hawaii) to determine whether slight genetic differences regulated host specificity. Through colonization studies performed in naïve squid hatchlings from both hosts, we found that all loci examined are important for specificity and host recognition. Complementation of null mutations in non-native <i>V. fischeri</i> with loci from the native <i>V. fischeri</i> caused a gain in fitness, resulting in competitive dominance in the non-native host. The competitive ability of these symbiotic loci depended upon the locus tested and the specific squid species in which colonization was measured. Our results demonstrate that multiple bacterial genetic elements can determine <i>V. fischeri</i> strain specificity between two closely related squid hosts, indicating how important genetic variation is for regulating conspecific beneficial interactions that are acquired from the environment.</p></div
<i>lux</i> operon data.
<p>Colonization assays 48-hour post-infection of juvenile (A) <i>Euprymna scolopes</i> and (B) <i>Euprymna tasmanica</i> by their respective wild-type (ES114 or ETJB1H), mutant, and complement strains of the <i>lux</i> operon for <i>Vibrio fischeri</i>. Infection efficiency data is plotted as the log values of the relative competitiveness index (RCIs), calculated by dividing the ratio of mutant to wild-type by the starting ratio <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101691#pone.0101691-Hussa1" target="_blank">[28]</a>. If the RCI is <1 the mutant strain was outcompeted by the wild-type, the wild-type strain was outcompeted by the mutant if the value is >1, and a RCI equal to 1 indicates no competitive difference. Data points represent individual animals and the position of the figures on the y axis is merely for spacing. Vertical line represents the median value of each data plot.</p
<i>msh</i> operon data.
<p>Colonization assays 48-hour post-infection of juvenile (A) <i>Euprymna scolopes</i> and (B) <i>Euprymna tasmanica</i> by their respective wild-type (ES114 or ETJB1H), mutant, and complement strains of <i>msh</i> genes for <i>Vibrio fischeri</i>. Infection efficiency data is plotted as the log values of the relative competitiveness index (RCIs), calculated by dividing the ratio of mutant to wild-type by the starting ratio <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101691#pone.0101691-Hussa1" target="_blank">[28]</a>. If the RCI is <1 the mutant strain was outcompeted by the wild-type, the wild-type strain was outcompeted by the mutant if the value is >1, and a RCI equal to 1 indicates no competitive difference. Data points represent individual animals and the position of the figures on the y axis is merely for spacing. Vertical line represents the median value of each data plot.</p
<i>pil</i> operon data.
<p>Colonization assays 48-hour post-infection of juvenile (A) <i>Euprymna scolopes</i> and (B) <i>Euprymna tasmanica</i> by their respective wild-type (ES114 or ETJB1H), mutant, and complement strains of <i>pil</i> genes for <i>Vibrio fischeri</i>. Infection efficiency data is plotted as the log values of the relative competitiveness index (RCIs), calculated by dividing the ratio of mutant to wild-type by the starting ratio <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0101691#pone.0101691-Hussa1" target="_blank">[28]</a>. If the RCI is <1 the mutant strain was outcompeted by the wild-type, the wild-type strain was outcompeted by the mutant if the value is >1, and a RCI equal to 1 indicates no competitive difference. Data points represent individual animals and the position of the figures on the y axis is merely for spacing. Vertical line represents the median value of each data plot.</p