Biology subjects

Mastronardi, K.

Publications and source records attributed to Mastronardi, K..

3 recordsLinked to original sources

bioRxiv2021

The ubiquitous terpene geosmin is a warning chemical

Known as the smell of earth after rain, geosmin is an odorous terpene detectable by humans at picomolar concentrations. Geosmin production is heavily conserved in actinobacteria, myxobacteria, cyanobacteria, and some fungi, but its biological activity is poorly understood. We theorized that geosmin was an aposematic signal used to indicate the unpalatability of toxin-producing microbes, discouraging predation by eukaryotes. Consistent with this hypothesis we found that geosmin and the related terpene 2-methylisoborneol reduced predation of Streptomyces coelicolor and Myxococcus xanthus by the bacteriophagous Caenorhabditis elegans. Predation was restored by the removal of both terpene biosynthetic pathways or deletion of the C. elegans ASE sensory neuron, and resulted in the death of the nematodes. Geosmin itself was non-toxic. This is the first warning chemical to be identified in bacteria or fungi, and suggests molecular signalling affects microbial predator-prey interactions in a manner similar to the well-studied visual markers of poisonous animal prey.

microbiology↗

bioRxiv2021

The Ran pathway uniquely regulates cytokinesis in cells with different fates in the early C. elegans embryo

Cytokinesis occurs at the end of mitosis and occurs due to the ingression of a contractile ring that cleaves the daughter cells. This process is tightly controlled to prevent cell fate changes or aneuploidy, and the core machinery is highly conserved among metazoans. Multiple mechanisms regulate cytokinesis, but their requirement in different cell types is not known. Here, we show that differently fated AB and P1 cells in the early C. elegans embryo have unique cytokinesis kinetics supported by distinct levels and cortical patterning of myosin. Through perturbation of polarity regulators and the generation of stable tetraploid strains, we demonstrate that these differences depend on both cell fate and size. Additionally, these parameters could influence the Ran pathway, which coordinates the contractile ring with chromatin position, and controls cytokinesis differently in AB and P1 cells. Our findings demonstrate the need to consider multiple parameters when modeling ring kinetics.

cell biology↗

bioRxiv2020

Multi-tissue patterning drives anterior morphogenesis of the C. elegans embryo

Complex structures derived from multiple tissue types are challenging to study in vivo, and our knowledge of how cells from different tissues are coordinated is limited. Model organisms have proven invaluable for improving our understanding of how chemical and mechanical cues between cells from two different tissues can govern specific morphogenetic events. Here we used Caenorhabditis elegans as a model system to show how cells from three different tissues are coordinated to give rise to the anterior lumen. This poorly understood process has remained a black box for embryonic morphogenesis. Using various microscopy and software approaches, we describe the movements and patterns of epidermal cells, neuroblasts and pharyngeal cells that contribute to lumen formation. The anterior-most pharyngeal cells (arcade cells) may provide the first marker for the location of the future lumen and facilitate the patterning of the surrounding neuroblasts. These neuroblast patterns control the rate of migration of the anterior epidermal cells, whereas the epidermal cells ultimately reinforce and control the position of the future lumen, as they must join with the pharyngeal cells for their epithelialization. Our studies are the first to characterize anterior morphogenesis in C. elegans in detail and should lay the framework for identifying how these different patterns are controlled at the molecular level.

developmental biology↗