Biology subjects

Runge, M.

Publications and source records attributed to Runge, M..

4 recordsLinked to original sources

bioRxiv2026

Chloroplast ABC peptide transporters TAP1, NAP8, and ATH12 are essential for heat-induced peptide export and play a key role in thermotolerance in Arabidopsis thaliana.

ATP-binding cassette (ABC) transporters mediate substrate translocation across membranes by using energy from ATP hydrolysis. While ABC peptide exporters have been characterized in the mitochondria of metazoans and yeast, corresponding chloroplast peptide transport systems in plants remain uncharacterized. Using in silico and experimental approaches, we identify three previously uncharacterized Arabidopsis thaliana ABCB half-transporters - TAP1, NAP8, and ATH12 - that localize to the chloroplast inner envelope and form homodimers. These proteins are phylogenetically related to known peptide exporters, and functional complementation in Saccharomyces cerevisiae demonstrates that each plant transporter can rescue the heat sensitivity of a{Delta} mdl1 mutant, indicating conserved peptide export activity. In chloroplast peptide efflux assays, peptide export upon heat stress was strongly reduced only in the tap1 nap8 ath12 triple mutant, but not in single or double mutants, indicating functional redundancy. Furthermore, mass spectrometry of chloroplast supernatants revealed an abundance of thylakoid-derived hydrophilic peptides in the wild type, predicted to have antioxidant activity. Under heat stress, the triple mutant displayed increased sensitivity, characterized by reduced biomass, chlorophyll and carotenoid content, and compromised photosynthetic efficiency. Comprehensive analyses revealed altered redox homeostasis in the triple mutant, including modified antioxidant dynamics, differential antioxidant enzyme activities, and distinct gene expression profiles compared with the wild type. Our findings demonstrate that TAP1, NAP8, and ATH12 constitute a chloroplast peptide export system required for efficient peptide release under heat stress, with a role in Arabidopsis thermotolerance. These results provide new insights into organellar peptide transport and its integration with stress mitigation mechanisms in plants.

plant biology↗

bioRxiv2024

Cerebellar encoding of prior knowledge of temporal statistics

We possess the ability to anticipate and preempt occurrences under familiar circumstances, which suggests a reliance on prior experience with regularities in our environment1-6, especially when observations become more uncertain. We know little about the neural mechanisms that can learn the probabilities of events in the environment and use this prior experience to guide actions. To examine this, we studied a rudimentary predictive behavior, eyeblink conditioning, and asked whether a simple effector like the eyelid could adapt its movements to varying probabilities of environmental events that reflect different degrees of uncertainty. We found that predictive eyeblink behavior systematically changed almost all its properties according to the temporal statistics of stimulus probability distributions. We also found that the activity of cerebellar Purkinje cells and putative molecular layer interneurons changed concomitantly with temporal statistics of the stimuli and with behavior. Targeted optogenetic perturbation of Purkinje cells during critical time windows severely attenuated the predictive behavior but left reflexive eyeblinks intact. Furthermore, we discovered a novel Purkinje cell complex spike signal coinciding with the onset of the earliest probable time interval in prior distributions with high uncertainty. This signal could not be explained as a motor or sensory correlate and appears to be anticipatory in nature. Theoretical modeling results pointed to a possible synaptic mechanism for how Purkinje cells could encode prior experience of environmental statistics in their activity through the juxtaposition of long-term depression and potentiation dynamics.

neuroscience↗

bioRxiv2023

Cross-sector collaboration reduces SARS-CoV-2 risk in deer

One Health helps achieve optimal health outcomes for people, animals, plants, and their shared environments. We describe a multidisciplinary effort to better understand and mitigate SARS-CoV-2 spread in white-tailed deer across One Health sectors. We first framed the risk problem with three governance sectors that manage captive and wild deer and human public health. The framing included the objectives for each sector, interactions that facilitate human-to-deer and deer-to-deer transmission, and alternatives intended to reduce risk. We then developed a dynamic compartmental model that linked wild and captive deer herds and humans and simulated SARS-CoV-2 dynamics. For baseline conditions, we estimated that median SARS-CoV-2 prevalence in wild and captive herds varied between 0.03 - 0.07, incidence between 0.68 - 1.46, and probability of persistence between 0.64 - 0.97 across 120-day simulations. We then tested single-sector alternatives alone and in combination with other sector actions. We found that single sector alternatives varied in their ability to reduce transmission and that the best performing alternative required collaborative actions among wildlife management, agricultural management, and public health agencies.

ecology↗

bioRxiv2022

Live cell nanodot arrays uncover synergistic co-condensation of Wnt signalodroplets

Qualitative and quantitative analysis of transient signaling platforms in the plasma membrane has remained a key experimental challenge. Here, we have developed biofunctional nanodot arrays (bNDAs) to spatially control dimerization and clustering of cell surface receptors at nanoscale. High-contrast bNDAs with spot diameters of [~]300 nm were obtained by capillary nanostamping of BSA bioconjugates, which were subsequently biofunctionalized by reaction with tandem anti- GFP clamp fusions. We achieved spatially controlled assembly of active Wnt signalosomes at the nanoscale in the plasma membrane of live cells by capturing the co-receptor Lrp6 into bNDAs via an extracellular GFP tag. Strikingly, we observed co-recruitment of co-receptor Frizzled-8 as well as the cytosolic scaffold proteins Axin-1 and Disheveled-2 into Lrp6 nanodots in the absence of ligand. Density variation and the high dynamics of effector proteins uncover highly cooperative liquid-liquid phase separation (LLPS)-driven assembly of Wnt "signalodroplets" at the plasma membrane, pinpointing the synergistic effects of LLPS for Wnt signaling amplification. These insights highlight the potential of bNDAs for systematically interrogating nanoscale signaling platforms and condensation at the plasma membrane of live cells.

biophysics↗