Abstract figure legend Knollenorgans of mormyrid fish transmit high-frequency electrical signals. Mormyrid electric fish (top) have Knollenorgans (electroreceptors) on their bodies (red and blue dots) that detect electrical stimuli (middle, left) through an electrical tuning mechanism. The receptors act as linear bandpass filters (middle, centre) that transduce different ranges of frequencies from about 1–20 kHz (middle, right). Rectification and non-linear thresholding (bottom, left) convert the responses to well-timed spikes (bottom, right), which vary across receptors but faithfully transmit signals well above 10 kHz.

Abstract figure legend Low-capacity runner (LCR) and high-capacity runner (HCR) rats were subjected to 6 weeks of voluntary wheel running (VWR) or sedentary control (CTRL) beginning at weaning. Animals underwent comprehensive metabolic phenotyping, mitochondrial respiration assays, and transcriptomic/proteomic profiling in skeletal muscle and liver. VWR reduced adiposity and improved glucose tolerance selectively in LCR, with minimal changes observed in HCR. Mitochondrial respiration was unaltered in skeletal muscle but increased in liver of HCR only. Skeletal muscle exhibited more differentially expressed genes (DEGs) and differentially abundant proteins (DAPs) in LCR. Overlap in molecular signatures across genotypes in response to VWR was modest, indicating genotype-specific adaptations to early-life exercise.

Abstract figure legend Mild dehydration prior to resistance exercise (RE) increased plasma and urine osmolality and USG. Findings indicated that in the dehydration condition, S6K activation, REDD1, active-cathepsin L, and H₂O₂ concentrations were greater than the euhydration condition. These changes were accompanied by increased muscle water content in the dehydration condition, despite a smaller muscle fibre CSA than in the euhydrated condition.

Abstract figure legend Using an in vitro rat retinal slice preparation, we performed whole-cell recordings from rod bipolar cells (RBCs) to investigate the functional properties of the hyperpolarization- and cyclic nucleotide-activated channels (HCN or I_h channels) in these cells. From the recordings, we developed a Hodgkin–Huxley-type model for the time and voltage dependence of I_h. Immunolabelling against HCN2 indicated expression of I_h channels in dendrites, cell body and axon terminals of RBCs (red). Applying a ZAP current stimulus revealed bandpass frequency–response characteristics that could be eliminated by blocking I_h channels with Cs⁺ (grey). Dynamic clamp experiments suggested that injecting a digital I_h conductance (+g_h) after blocking the intrinsic I_h with Cs⁺ rescued the bandpass filtering and injecting a negative I_h conductance (−g_h) negated the intrinsic I_h conductance and blocked bandpass filtering. Together with additional results from computational modelling, we conclude that I_h is both necessary and sufficient for the bandpass frequency–response characteristics of RBCs.

Abstract figure legend Unilateral training intervention reduced the variance in common synaptic input (CSI-V), which was associated with decreased variability in force steadiness (CovF) in both the trained and contralateral untrained limbs. On the exercised side, the increase in maximal voluntary force (MVF) was accompanied by a higher proportion of common synaptic input (CSI), a lower motor unit recruitment threshold (RT), enhanced persistent inward current (PIC) amplitude and increased neural drive. In contrast, the contralateral untrained limb exhibited higher shared synaptic input and a lower RT but with unaltered PIC amplitude and neural drive (⇋). Overall, these adaptations resulted in a 14% increase in MVF in the exercised limb and a 6% increase in the untrained limb.