Biology subjects

Reicher, N.

Publications and source records attributed to Reicher, N..

3 recordsLinked to original sources

bioRxiv2025

The Crunchometer: A Low-Cost, Open-Source Acoustic Analysis of Feeding Microstructure

Elucidating the neuronal circuits that govern appetite requires precise, high-resolution monitoring of the microstructure of solid food consumption, a need unmet by existing tools, which are either costly or lack the temporal resolution to align feeding events with neuronal activity. To overcome this, we developed the Crunchometer, a low-cost, open-source acoustic system that uses computational algorithms to generate high-resolution feeding ethograms from the sounds produced during solid food consumption. Validation across energy states (hunger/satiety) confirmed its sensitivity to changes in feeding microstructure, and the system reliably detected semaglutide-induced suppression of intake and reduced preference for a high-fat diet. Leveraging its seamless integration with in vivo recordings in freely behaving mice, we paired the Crunchometer with lateral hypothalamus (LH) electrophysiology to identify "meal-related" neurons that track entire meals rather than individual bouts. Calcium imaging further revealed that distinct subsets of LH GABAergic and glutamatergic neurons were tuned to feeding only, to licking only, or to both behaviors. Thus, LH neuronal ensembles differentially encode the consumption of solid food versus liquid sucrose. These findings demonstrate that the Crunchometer is a robust, accessible platform for dissecting the neural correlates of feeding behavior at the resolution of a single bite. Significance statementThe Crunchometer is a low-cost, open-source technology that democratizes feeding analysis, enabling the precise dissection of neuronal circuits involved in appetite to advance therapies for obesity and eating disorders.

neuroscience↗

bioRxiv2023

Highly conserved, positively charged tandem repeats mediate multimerization of ice nucleation proteins

In nature, frost can form at a few degrees below 0 {degrees}C. However, this process requires the assembly of tens of thousands of ice-like water molecules that align together to initiate freezing at these relatively high temperatures. Water ordering on this scale is mediated by the ice nucleation proteins of common environmental bacteria like Pseudomonas syringae and P. borealis. However, individually, these 100-kDa proteins are too small to organize enough water molecules for frost formation, and it is not known how giant, megadalton-sized multimers, which are crucial for ice nucleation at high sub-zero temperatures, form. The ability of multimers to self-assemble was suggested when the transfer of an ice nucleation protein gene into Escherichia coli led to efficient ice nucleation. Here we demonstrate that a positively-charged sub-domain at the C-terminal end of the central beta-solenoid of the ice nucleation protein is crucial for multimerization. Truncation, relocation, or change of the charge of this subdomain caused a catastrophic loss of ice nucleation ability. Cryo-electron tomography of the recombinant E. coli showed that the ice nucleation protein multimers form fibres that are [~] 5 nm across and up to 200 nm long. A model of these fibres as an overlapping series of antiparallel dimers can account for all their known properties and suggests a route to making cell-free ice nucleators for biotechnological applications.

biochemistry↗

bioRxiv2022

Structure and Protein-Protein Interactions of Ice Nucleation Proteins Drive Their Activity

ABSTRACTMicrobially-produced ice nucleating proteins (INpro) are unique molecular structures with the highest known catalytic efficiency for ice formation. Their critical role in rain formation and frost damage of crops together with their diverse commercial applications warrant an in-depth under-standing of their inherent ice nucleation mechanism. We used the machine-learning based software Al-phaFold to develop the first ab initio structural model of a bacterial INpro which is a novel beta-helix structure consisting of repeated stacks of two beta strands connected by two sharp turns. Using the synchrotron radiation circular dichroism, we validated the {beta}-strand content of the model. Combining functional studies of purified recombinant INpro, electron microscopy and modeling, we further demonstrate that the formation of dimers and higher-order oligomers is key to INpro activity. This work presents a major advance in understanding the molecular foundation for bacterial ice-nucleation activity and the basis for investigating the mechanistic role of INpro-induced ice formation in the atmosphere, and for commercial design and production of ice-nucleating particles for industrial applications.

microbiology↗