Natural commensal microbes induce internal hatching in C. elegans

Area of Science:

• Microbiology
• Developmental Biology
• Genetics

Background:

• The microbiome plays a crucial role in host life-history trait plasticity.
• Internal egg hatching (facultative vivipary) is a stress-adaptive reproductive strategy in C. elegans, typically associated with starvation or pathogens.

Purpose of the Study:

• To investigate how naturally associated bacterial strains influence internal egg hatching in C. elegans.
• To elucidate the host endocrine pathways involved in mediating these microbiome-induced reproductive changes.

Main Methods:

• C. elegans were cultured on various naturally associated bacterial strains.
• Internal egg hatching rates, reproductive window, progeny, and lifespan were quantified.
• Genetic analyses were performed to identify host genes and pathways involved, focusing on the insulin signaling pathway (e.g., DAF-16/FOXO).

Main Results:

• Four specific bacterial strains (Ochrobactrum BH3, Lelliottia JUb66, Pantoea BIGb0393, Enterobacter CEent1) induced high levels of internal hatching (28-57%) in late-adult C. elegans, unlike control E. coli OP50 (<5%).
• These bacteria extended the reproductive window, with trends toward reduced progeny and lifespan.
• Bacterial strain BH3 acted via DAF-16/FOXO, while the other three γ-proteobacterial strains acted independently of DAF-16, indicating differential pathway engagement.

Conclusions:

• Naturally associated microbiome members can differentially modulate host endocrine signaling to shape reproductive outcomes.
• Microbial cues can influence life-history plasticity by interacting with conserved host pathways like insulin signaling.
• These findings highlight the potential of leveraging microbiomes to influence host reproductive strategies and life-history traits.