Can I still eat it? Using problem-based learning to test the 5-second rule and promote scientific literacy.

Defining appropriate student learning outcomes for general education science courses is a daunting task. We must ask ourselves how to best prepare our students to understand the role of science in their lives and in society at large. In the era of social media and armchair experts, life-changing scientific advancements such as vaccination are being dismissed or actively resisted, emphasizing the critical need to teach science literacy skills.

High Levels of the Xenorhabdus nematophila Transcription Factor Lrp Promote Mutualism with the Steinernema carpocapsae Nematode Host.

bacteria are mutualistic symbionts of nematodes and pathogens of insects. The global regulator Lrp controls the expression of many genes involved in both mutualism and pathogenic activities, suggesting a role in the transition between the two host organisms. We previously reported that natural populations of exhibit various levels of Lrp expression and that cells expressing relatively low levels of Lrp are optimized for virulence in the insect The adaptive advantage of the high-Lrp-expressing state was not established.

The Global Transcription Factor Lrp Controls Virulence Modulation in Xenorhabdus nematophila.

Unlabelled: The bacterium Xenorhabdus nematophila engages in phenotypic variation with respect to pathogenicity against insect larvae, yielding both virulent and attenuated subpopulations of cells from an isogenic culture. The global regulatory protein Lrp is necessary for X. nematophila virulence and immunosuppression in insects, as well as colonization of the mutualistic host nematode Steinernema carpocapsae, and mediates expression of numerous genes implicated in each of these phenotypes.

NilD CRISPR RNA contributes to Xenorhabdus nematophila colonization of symbiotic host nematodes.

The bacterium Xenorhabdus nematophila is a mutualist of entomopathogenic Steinernema carpocapsae nematodes and facilitates infection of insect hosts. X. nematophila colonizes the intestine of S.

The syp enhancer sequence plays a key role in transcriptional activation by the σ54-dependent response regulator SypG and in biofilm formation and host colonization by Vibrio fischeri.

Biofilm formation by Vibrio fischeri is a complex process that requires multiple regulators. One such regulator, the NtrC-like response regulator SypG, controls biofilm formation and host colonization by V. fischeri via its impact on transcription of the symbiosis polysaccharide (syp) locus.

It takes a village: ecological and fitness impacts of multipartite mutualism.

Microbial symbioses, in which microbes have either positive (mutualistic) or negative (parasitic) impacts on host fitness, are integral to all aspects of biology, from ecology to human health. In many well-studied cases, microbial symbiosis is characterized by a specialized association between a host and a specific microbe that provides it with one or more beneficial functions, such as novel metabolic pathways or defense against pathogens. Even in relatively simple associations, symbiont-derived benefits can be context dependent and influenced by other host-associated or environmental microbes.

The putative hybrid sensor kinase SypF coordinates biofilm formation in Vibrio fischeri by acting upstream of two response regulators, SypG and VpsR.

Colonization of the Hawaiian squid Euprymna scolopes by the marine bacterium Vibrio fischeri requires the symbiosis polysaccharide (syp) gene cluster, which contributes to symbiotic initiation by promoting biofilm formation on the surface of the symbiotic organ. We previously described roles for the syp-encoded response regulator SypG and an unlinked gene encoding the sensor kinase RscS in controlling syp transcription and inducing syp-dependent cell-cell aggregation phenotypes. Here, we report the involvement of an additional syp-encoded regulator, the putative sensor kinase SypF, in promoting biofilm formation.

RscS functions upstream of SypG to control the syp locus and biofilm formation in Vibrio fischeri.

Two-component signal transduction systems, composed of sensor kinase (SK) and response regulator (RR) proteins, allow bacterial cells to adapt to changes such as environmental flux or the presence of a host. RscS is an SK required for Vibrio fischeri to initiate a symbiotic partnership with the Hawaiian squid Euprymna scolopes, likely due to its role in controlling the symbiosis polysaccharide (syp) genes and thus biofilm formation. To determine which RR(s) functions downstream of RscS, we performed epistasis experiments with a library of 35 RR mutants.

Two-component response regulators of Vibrio fischeri: identification, mutagenesis, and characterization.

Two-component signal transduction systems are utilized by prokaryotic and eukaryotic cells to sense and respond to environmental stimuli, both to maintain homeostasis and to rapidly adapt to changing conditions. Studies have begun to emerge that utilize a large-scale mutagenesis approach to analyzing these systems in prokaryotic organisms. Due to the recent availability of its genome sequence, such a global approach is now possible for the marine bioluminescent bacterium Vibrio fischeri, which exists either in a free-living state or as a mutualistic symbiont within a host organism such as the Hawaiian squid species Euprymna scolopes.

A novel, conserved cluster of genes promotes symbiotic colonization and sigma-dependent biofilm formation by Vibrio fischeri.

Vibrio fischeri is the exclusive symbiont residing in the light organ of the squid Euprymna scolopes. To understand the genetic requirements for this association, we searched a library of V. fischeri transposon insertion mutants for those that failed to colonize E.