Biology subjects

Swenson, C.

Publications and source records attributed to Swenson, C..

4 recordsLinked to original sources

bioRxiv2026

Low Intensity Multi-Channel Steering TMS Array for Network Level Neuromodulation

Objective: Low-intensity transcranial magnetic stimulation (LI-TMS) is being investigated as a gel-free alternative to transcranial electrical stimulation (tES), but existing systems remain almost exclusively single-channel and cannot electronically steer the induced electric field. We present the design, modeling, and experimental measurement of a wearable whole-head, multichannel, steerable LI-TMS array. Methods: The system comprises a 102-channel conformal coil array with independently controlled drivers capable of arbitrary waveform synthesis, together with a boundary element fast multipole method (BEM-FMM) framework that computes the coil currents required to produce prescribed cortical field patterns. A 12-channel prototype was characterized by coil-current, electric-field, and thermal measurements. Results: The prototype produced a peak primary electric field of approximately 1 V/m measured in air 4 cm from the inner helmet surface. Whole-array modeling attained cortical fields of up to 1.5 V/m, reproduced the field distribution of a clinically validated low-intensity stimulator to within 3%-5%, and demonstrated focal targeting of the dorsolateral prefrontal cortex, simultaneous delivery of electric field to the default mode network nodes, and synthesis of electric fields following the traveling alpha wave. Conclusion: Electronically steerable, whole-head LI-TMS is feasible using accessible microprocessor-controlled power electronics. Significance: The array reaches the cortical field regime of tES without scalp contact or the associated shunting of current through the scalp, offering a route to testing network-level, phaselocked weak-field neuromodulation.

bioengineering↗

bioRxiv2025

Spatially-resolved Photoproximity Profiling of MYC Identifies a MYC-BAF Liability in Cancer Cells

The c-MYC transcription factor is aberrantly expressed in most human cancers to enhance expression of proliferative gene programs. Owing to its pseudo-ordered structure and reliance on extensive and dynamic protein-protein interactions in distinct transcriptional regulatory complexes, defining context-specific MYC interactors has remained challenging. Therefore, mapping MYC-centered complex topologies in disease relevant models could identify components critical for its function which may serve as therapeutic targets in MYC-driven cancers. Here, we present a matched pair of photoproximity probes coupled with quantitative proteomics which enable context-dependent mapping of protein complex topology inside cells. We applied this spatially resolved, intracellular photoproximity (siPROX) profiling workflow to map MYC interactomes across temporal, spatial and disease-relevant contexts. Basal and inhibitor-treated profiles confirmed interactions with a wide range of known chromatin-associated transcriptional regulatory factors that define the extended MYC transcriptional bubble in live cells. Time-resolved mapping of inhibitor treated cells identified dynamic remodeling of numerous transcriptional regulatory factors and identified several BAF complex members (e.g., PBRM1 and SMARCC1)1 that persist in the presence of bromodomain inhibition. Furthermore, spatial MYC topology maps in small cell lung cancer cells confirmed the presence of BAF complex members under conditions where MYC induced target gene expression, altered cell morphology and enhanced proliferation. Lastly, loss of BAF function via inhibition of SMARCA2/4 ATPase activity resulted in rapid loss of chromatin-bound and nuclear MYC levels, downregulation of MYC-dependent transcripts and MYC-specific cell growth in several cancer cell models. Together, these data highlight the potential for siPROX to identify spatially resolved, dynamic TF interactors and highlight MYC-proximal BAF interactions as a targetable liability to regulate MYC-dependent transcription and proliferation.

cancer biology↗

bioRxiv2025

Spatiotemporal dynamics of nearshore fish communities in Casco Bay, Maine

AO_SCPLOWBSTRACTC_SCPLOWNearshore regions in the Gulf of Maine are highly variable habitats acted upon by processes operating on multiple spatial scales and levels of biological organization. As such, they facilitate the reproduction, growth, and migration of many fish species, and are particularly tied to the life histories of many forage fishes. Temperatures in the Gulf of Maine have rapidly increased in recent decades, which may be driving changes in nearshore ecosystems. Here, we use 11 years of summer beach seine survey data within Casco Bay, Maine, to illustrate temperature-related changes to community structure. Further, we use Atlantic herring (Clupea harengus) and Atlantic silversides (Menidia menidia) as focal species to describe the effects of temperature on individual growth rates and relative abundance. The progression of seasonal use patterns and relative abundance in the nearshore with seasonal warming is evident; species that have cooler preferred temperatures are caught less frequently in the nearshore regions in late summer, when temperatures are highest. Increased temperatures were associated with significantly higher silverside growth rates and community compositions dominated by silverside. Temperature alone did not explain interannual variation in herring growth rates or predict herring-dominated nearshore community composition, and there is evidence that density-dependence may be more important to herring population dynamics. Monitoring nearshore ecosystems could provide critical insight into the dynamics of species that use these areas to facilitate reproduction, growth, and migration, and could therefore be used to identify potential changes to Gulf of Maine community and trophic ecology.

ecology↗

bioRxiv2022

Orthogonal synthetases for polyketide precursors

The absence of orthogonal aminoacyl-tRNA synthetases that accept non-L--amino acids is the primary bottleneck hindering the in vivo translation of sequence-defined hetero-oligomers. Here we report PylRS enzymes that accept -hydroxy acids, -thio acids, N-formyl-L--amino acids, and -carboxyl acid monomers (malonic acids) that are formally precursors to polyketide natural products. These monomers are all accommodated and accepted by the translation apparatus in vitro. High-resolution structural analysis of the complex between one such PylRS enzyme and a meta-substituted 2-benzylmalonate derivative reveals an active site that discriminates pro-chiral carboxylates and accommodates the large size and distinct electrostatics of an -carboxyl acid substituent. This work emphasizes the potential of PylRS-derived enzymes for acylating tRNA with monomers whose -substituent diverges significantly from the -amine embodied in proteinogenic amino acids. These enzymes could act in synergy with natural or evolved ribosomes to generate diverse sequence-defined non-protein hetero-oligomers.

synthetic biology↗