"Failure To Launch": Development of a Reproductive Organ Linked to Symbiotic Bacteria

Area of Science:

• Microbiology
• Developmental Biology
• Symbiosis Research

Background:

• Animal development is significantly influenced by microbial symbionts.
• The Hawaiian bobtail squid (Euprymna scolopes) hosts symbiotic bacteria in its light organ and a community in its accessory nidamental gland (ANG).
• The role of environmental bacteria in the development of the ANG is not well understood.

Purpose of the Study:

• To investigate the influence of environmental bacteria on the development of the accessory nidamental gland (ANG) in Euprymna scolopes.
• To determine if specific bacterial groups are associated with ANG development.
• To explore the potential for manipulating ANG community composition.

Main Methods:

• Squid were raised in laboratory conditions with experimentally manipulated exposure to environmental microorganisms.
• Bacterial communities in the ANG and on substrate were analyzed using sequencing.
• Specific bacterial strains were introduced to assess colonization and impact on ANG development.

Main Results:

• Depletion of environmental bacteria led to absent or stunted ANG development, independent of the light organ symbiont Vibrio fischeri.
• Exposure to natural substrate with native microbiota resulted in normal ANG development and community composition similar to wild-caught squid.
• Bacterial groups such as Verrucomicrobia were linked to ANG development, and specific strains like Leisingera sp. JC1 could colonize the ANG.

Conclusions:

• Environmental bacteria are required for the proper development of the accessory nidamental gland (ANG) in Euprymna scolopes.
• This study provides the first example of complete organ development dependent on symbiotic bacteria in an animal host.
• Euprymna scolopes serves as a valuable model for studying the impact of beneficial bacteria on animal development.