Post doc opportunity with Dr. Carl Hirschie Johnson at Vanderbilt University

Postdoctoral Position: Evolution of Circadian Rhythms and Photoperiodism


Vanderbilt University, Nashville, USA: Laboratory of Dr. Carl Hirschie Johnson


The Position: Dr. Johnson is seeking a highly motivated postdoctoral fellow to study the evolution of circadian (daily) clocks and photoperiodism in bacteria by experimental and bioinformatics methods, including the use of an innovative experimental evolution approach.


Background: The field of circadian clocks received the Nobel Prize in Physiology or Medicine in 2017 for its progress towards understanding the mechanism of circadian oscillators. While these biological clocks display conserved properties from bacteria (especially cyanobacteria) to fungi, plants, insects, and vertebrates (including humans, of course), practically nothing is known about their evolution or about the selective pressure(s) that led to the evolution of these fascinating biological timekeepers. The laboratory of Dr. Johnson led the discoveries of circadian clocks in bacteria, in particular major contributions to the mechanism of the circadian system in cyanobacteria. Moreover, Dr. Johnson’s laboratory is the major (and practically the only) laboratory that has provided experimental support for the fitness advantage of circadian clocks (see PMCID: PMC21132, PMID:15324665, and PMCID: PMC3633149).


The Project: Inspired by studies from other laboratories of bacterial experimental evolution to relatively simple selective pressures, the Johnson Laboratory has undertaken an experimental evolution approach using E. coli (that does not exhibit circadian phenomena) under a variety of rhythmic environmental regimes to evolve clock-like behavior. This experimental evolution has been conducted for eight years by the technician in the laboratory, and is now exhibiting interesting phenotypes that need a conscientious and motivated postdoctoral fellow to characterize and analyze. The methodology will include genetic/bioinformatic methods (genome sequencing, analysis of adaptive mutations, RNAseq, etc.), physiological/imaging methods (to most fully characterize phenotypes using luminescent and/or fluorescent reporters), proteomic methods (analyzing gene expression patterns), and metabolomic methods (temporal changes in metabolism in response to rhythmic environments).

In addition to the experimental evolution project, the candidate will also be involved in analyses of the adaptive significance and mechanism of biological timekeeping in purple bacteria and cyanobacteria (see PMCID: PMC4794148). For an overall introduction to these research questions, see our review in Nature Reviews in Microbiology (PMCID: PMC5696799).


The Candidate: The ideal candidate has strong motivation and should ideally be driven by a passion for evolutionary biology. Expertise in genetic technology with bacteria and bioinformatics is a plus. The position requires the ability to independently take responsibility for the project, as well as strong teamwork & communication skills, problem-solving abilities, reliability, and effective time management.


Research environment and location: There are excellent facilities and collaborations available within the Vanderbilt University system, including other laboratories that study circadian clocks (e.g., the labs of Doug McMahon, Terry Page, and Beth Malow) and evolutionary biology in microbes (e.g., the labs of Antonis Rokas, Seth Bordenstein, Megan Behringer, and Ann Tate). Nashville is an exciting city with a relatively low cost of living and many artistic opportunities (especially music) as well as close proximity to nature.


For more information about my laboratory and our publications, see our website:


Interested applicants should contact Dr. Carl Johnson at: Please send a CV, your research interests, and a list of at least three referees.

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