Related Experiment Video
Updated: Dec 28, 2025
Assessing the Cellular Immune Response of the Fruit Fly, Drosophila melanogaster, Using an In Vivo Phagocytosis Assay
Published on: April 10, 2019
The Daisho Peptides Mediate Drosophila Defense Against a Subset of Filamentous Fungi
Lianne B Cohen1, Scott A Lindsay1, Yangyang Xu1
1Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States.
Abstract:
Fungal infections, widespread throughout the world, affect a broad range of life forms, including agriculturally relevant plants, humans, and insects. In defending against fungal infections, the fruit fly Drosophila melanogaster employs the Toll pathway to induce a large number of immune peptides. Some have been investigated, such as the antimicrobial peptides (AMPs) and Bomanins (Boms); many, however, remain uncharacterized. Here, we examine the role in innate immunity of two related peptides, Daisho1 and Daisho2 (formerly IM4 and IM14, respectively), found in hemolymph following Toll pathway activation. By generating a CRISPR/Cas9 knockout of both genes, Δdaisho, we find that the Daisho peptides are required for defense against a subset of filamentous fungi, including Fusarium oxysporum, but not other Toll-inducible pathogens, such as Enterococcus faecalis and Candida glabrata. Analysis of null alleles and transgenes revealed that the two daisho genes are each required for defense, although their functions partially overlap. Generating and assaying a genomic epitope-tagged Daisho2 construct, we detected interaction in vitro of Daisho2 peptide in hemolymph with the hyphae of F. oxysporum. Together, these results identify the Daisho peptides as a new class of innate immune effectors with humoral activity against a select set of filamentous fungi.
Insights
The Daisho peptides are crucial for fruit fly defense against specific fungal infections, acting as a new class of innate immune effectors. These peptides show humoral activity against filamentous fungi like Fusarium oxysporum.
Area of Science:
- * Insect immunity
- * Innate immune response
- * Molecular and cellular biology
Background:
- * Fungal infections pose a global threat to plants, humans, and insects.
- * The fruit fly, *Drosophila melanogaster*, utilizes the Toll pathway to activate immune peptides against fungal pathogens.
- * Many Toll-inducible immune peptides remain uncharacterized, including Daisho1 and Daisho2.
Purpose of the Study:
- * To investigate the role of Daisho1 and Daisho2 peptides in *Drosophila melanogaster*'s innate immunity.
- * To determine the specificity of Daisho peptides against different Toll-inducible pathogens.
- * To elucidate the mechanism of action for Daisho peptides in fungal defense.
Main Methods:
- * CRISPR/Cas9 gene editing was used to create a knockout of both *daisho* genes (Δ*daisho*).
- * Null alleles and transgenes were analyzed to assess the function of *daisho* genes.
- * Genomic epitope-tagged Daisho2 constructs were generated and assayed for *in vitro* interactions.
Main Results:
- * The Daisho peptides are essential for defense against a subset of filamentous fungi, notably *Fusarium oxysysporum*.
- * Daisho peptides are not required for defense against other pathogens like *Enterococcus faecalis* and *Candida glabrata*.
- * Both *daisho* genes contribute to defense, exhibiting partially overlapping functions, and Daisho2 interacts with *F. oxysysporum* hyphae.
Conclusions:
- * Daisho peptides represent a novel class of innate immune effectors in *Drosophila melanogaster*.
- * These peptides possess humoral activity specifically targeting certain filamentous fungi.
- * The findings expand our understanding of the molecular mechanisms underlying insect antifungal immunity.
