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Updated: Mar 19, 2026
Quantitative Analysis of Aspergillus nidulans Growth Rate using Live Microscopy and Open-Source Software
Published on: July 24, 2021
Endosome motility controls light-responsive reproductive development and secondary metabolite production in
Gaurav Kumar1,2, Jessica L Allen3, Livia D S Oster4
1Department of Biochemistry and Biophysics, Weill Cornell Medicine, New York, NY.
Abstract:
Filamentous fungi, such as Aspergillus species, use microtubule transport to move early endosomes. Other cargos, such as peroxisomes and mRNAs, "hitchhike" on early endosomes to move throughout the long hyphae of these organisms. In Aspergillus nidulans, peroxisomes hitchhike on early endosomes using the endosomal protein PxdA and the peroxisomal protein AcbdA. The HookA adaptor protein links endosomes to microtubule motors. Here, we set out to explore the physiological functions of peroxisome hitchhiking and endosome motility. A. nidulans has a complex life cycle that includes asexual and sexual reproduction. A. nidulans and other fungi within the Pezizomycotina subphylum are also notable for the vast number of secondary metabolites they produce. Light and other environmental conditions influence developmental decisions and secondary metabolite production. Here, we found that sexual reproduction is favored in the absence of endosome motility, even in the light, which normally promotes asexual reproduction. RNA sequencing of strains lacking endosome motility showed altered expression of genes involved in development. Unexpectedly, we observed altered expression of genes involved in secondary metabolism in strains lacking endosome motility and peroxisome hitchhiking. Using mass spectrometry, we found that the loss of endosome motility affected the biosynthesis of secondary metabolites, including sterigmatocystin, a carcinogenic mycotoxin that is a food contaminant. Finally, in a pathogenic species, Aspergillus fumigatus, we found that deletion of its PxdA homolog also significantly altered secondary metabolite production. Our work uncovers an unexpected link between organelle motility, developmental decisions in response to light, and secondary metabolite production in filamentous fungi.
Insights
Filamentous fungi use organelle motility for development and metabolite production. Disrupting endosome movement impacts sexual reproduction and alters secondary metabolite biosynthesis, including mycotoxins.
Area of Science:
- Cell Biology
- Mycology
- Biochemistry
Background:
- Filamentous fungi like Aspergillus utilize microtubule transport for organelle movement, with early endosomes serving as crucial transport vehicles.
- Peroxisomes and mRNAs hitchhike on early endosomes, facilitated by proteins like PxdA and AcbdA, enabling their transport within long hyphae.
- Organelle motility is essential for cellular functions, but its specific roles in fungal development and metabolism remain incompletely understood.
Purpose of the Study:
- To investigate the physiological functions of peroxisome hitchhiking and endosome motility in Aspergillus.
- To explore the impact of impaired organelle motility on fungal development, particularly in response to light cues.
- To determine the relationship between endosome motility and the production of secondary metabolites in filamentous fungi.
Main Methods:
- Utilized Aspergillus nidulans strains with defects in endosome motility and peroxisome hitchhiking.
- Employed RNA sequencing to analyze gene expression changes in response to altered organelle motility.
- Applied mass spectrometry to quantify secondary metabolite production and identify affected pathways.
Main Results:
- Asexual reproduction, typically light-induced, was suppressed in favor of sexual reproduction when endosome motility was absent.
- Gene expression analysis revealed significant alterations in genes related to development and secondary metabolism in strains lacking endosome motility.
- Loss of endosome motility and peroxisome hitchhiking disrupted the biosynthesis of secondary metabolites, including the mycotoxin sterigmatocystin.
- Deletion of the PxdA homolog in Aspergillus fumigatus also led to significant changes in secondary metabolite profiles.
Conclusions:
- Endosome motility plays a critical, previously unrecognized role in regulating developmental decisions, including light-mediated responses, in filamentous fungi.
- Organelle motility is intricately linked to secondary metabolite production, affecting the biosynthesis of crucial compounds like mycotoxins.
- These findings reveal a novel connection between cellular transport mechanisms, fungal development, and the production of bioactive compounds.
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