Biology subjects

Villasante, C. M.

Publications and source records attributed to Villasante, C. M..

3 recordsLinked to original sources

bioRxiv2025

Compartmentalized above- and belowground defenses in Tanacetum vulgare are tailored to localized antagonists

Specialized metabolites, specially terpenoids, play a key role in plant defense. However, how terpenoid diversity governs inducible chemistry and root architectural development remain poorly understood. We used a combination of high-throughput root phenotyping and targeted metabolite profiling to examine three leaf terpenoid chemotypes of common tansy (Tanacetum vulgare). Using a phenotyping platform, we tested whether (i) root-chewing wireworms induce root terpenoids locally and alter shoot terpenoids systemically, (ii) phloem-feeding aphids elicit chemotype-dependent responses, and (iii) chemotypes differ in root-system development. After root establishment, the plants were exposed to wireworms (Agriotes spp.) and aphids (Macrosiphoniella tanacetaria), both separately and together, and were then monitored for 60 days. The chemotypes differed in inducible chemistry and root architecture. Chemotype 1 developed the fastest-growing root systems and the highest root:shoot ratios. Wireworms increased stored root sesquiterpenoid levels by more than twofold in chemotypes 1 and 2, whereas chemotype 3 was largely unresponsive. Aphids didn t alter root terpenoids, but significantly increased leaf monoterpenoid emissions in chemotype 1 without affecting stored pools. Therefore, storage and emission were decoupled and depended on both organ and chemotype. Our analysis reveals a compartmentalized, chemotype-specific defense strategy in tansy, highlighting the coordinated regulation of the root system and inducible chemistry. HighlightIn Tanacetum vulgare, wireworms boost root sesquiterpenoids and aphids elevate leaf monoterpenoid emissions; chemotype governs terpenoid defense and root system architecture.

plant biology↗

bioRxiv2023

Nanomechanics of wild-type and mutant dimers of the tip-link protein protocadherin 15

Mechanical force controls the opening and closing of mechanosensitive ion channels atop the hair bundles of the inner ear. The filamentous tip link connecting transduction channels to the tallest neighboring stereocilium modulates the force transmitted to the channels and thus changes their probability of opening. Each tip link comprises four molecules: a dimer of protocadherin 15 and a dimer of cadherin 23, all of which are stabilized by Ca2+ binding. Using a high-speed optical trap to examine dimeric PCDH15, we find that the proteins configuration is sensitive to Ca2+ and that the molecule exhibits limited unfolding at a physiological Ca2+ concentration. PCDH15 can therefore modulate its stiffness without undergoing large unfolding events in physiological Ca2+ conditions. The experimentally determined stiffness of PCDH15 accords with published values for the stiffness of the gating spring, the mechanical element that controls the opening of mechanotransduction channels. When PCDH15 has a point mutation, V507D, associated with non-syndromic hearing loss, unfolding events occur more frequently under tension and refolding events occur less often than in the wild-type protein. Our results suggest that the maintenance of appropriate tension in the gating spring is critical to the appropriate transmission of force to transduction channels, and hence to hearing.

biophysics↗

bioRxiv2020

Measurement of hindered diffusion in complex geometries for high-speed single-molecule experiments

In a high-speed single-molecule experiment, a protein is tethered between two substrates that are manipulated to exert force on the system. To avoid nonspecific interactions between the protein and nearby substrates, the protein is usually attached to the substrates through long, flexible linkers. This approach precludes measurements of mechanical properties with high spatial and temporal resolution, for rapidly exerted forces are dissipated into the linkers. Because mammalian hearing operates at frequencies reaching tens to hundreds of kilohertz, the mechanical processes that occur during transduction are of very short duration. Single-molecule experiments on the relevant proteins therefore cannot involve long tethers. We previously characterized the mechanical properties of protocadherin 15 (PCDH15), a protein essential for human hearing, by tethering an individual monomer through very short linkers between a probe bead held in an optical trap and a pedestal bead immobilized on a glass coverslip. Because the two confining surfaces were separated by only the length of the tethered protein, hydrodynamic coupling between those surfaces complicated the interpretation of the data. To facilitate our experiments, we characterize here the anisotropic and position-dependent diffusion coefficient of a probe in the presence of an effectively infinite wall, the coverslip, and of the immobile pedestal.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biophysics↗