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Becoming a Friend Instead of a Foe

An Attempt to Create Mutualistic Symbiosis


Author(s)

Melissa R. Eslinger
Department of Chemistry and Life Science
United States Military Academy
melissa.eslinger@westpoint.edu
Cameron B. Marlow
Department of Chemistry and Life Science
United States Military Academy
cameron.marlow@westpoint.edu

Abstract

This case study centers on symbiotic relationships between insects and bacteria using Drosophila melanogaster, the common fruit fly, and the recently discovered bacterial species Sodalis praecaptivus. Until recently, the only known Sodalis species of bacteria were symbiotically associated with several different species of insects. However, free-living non-symbiont Sodalis species are being tested in several different insect species to determine if they can transition into symbiotic relationships. A pre-class assignment (see Supplemental Materials) directs students to read an open access research journal article providing a comprehensive review of S. praecaptivus and describing an experimental weevil model that parallels that of the fruit fly. A PowerPoint presentation shown in class (see Supplemental Materials) provides further background before students work in small groups to complete the case study focusing on results from D. melanogaster and S. praecaptivus model experiments.  Although developed for a genetics course, this interrupted case is appropriate for an upper-level biology course. It can be completed within a 75-minute class meeting, or adapted for shorter time periods.


Objectives

  • Understand fundamental bacteria-insect symbiotic relationships.
  • Understand how to select organisms and develop an experimental design to test scientific hypotheses.
  • Analyze and interpret collected data from a symbiotic designed experiment.

Keywords

Symbiosis; bacteria-insect symbiosis; experimental modeling; Drosophila; Sodalis; quorum sensing: endosymbiont; mutation; genome degeneration;

Topical Areas

N/A

Educational Level

Undergraduate lower division, Undergraduate upper division

Format

PDF, PowerPoint

Type / Methods

Interrupted, Journal Article

Language

English

Subject Headings

Biology (General)  |   Genetics / Heredity  |   Microbiology  |  


Date Posted

01/25/2021

Teaching Notes

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Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

Supplemental Materials

Below are a Pre-Class Assignment to prepare students for the case study, and a PowerPoint presentation to be used in class by the instructor to provide additional details about the D. melanogaster and S. praecaptivus experiment described in the case study handout.

  
  Pre-Class Assignment
  
  Presentation (~3.2 MB)

Answer Key

Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.

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