Biology subjects

Ong, S.

Publications and source records attributed to Ong, S..

3 recordsLinked to original sources

bioRxiv2025

Comparative transcriptomics of lateral hypothalamic cell types reveals conserved growth hormone-tachykinin dynamics in feeding

The lateral hypothalamus (LH) is a highly heterogeneous brain region regulating hunger and motivated behaviors. In zebrafish, the LH shows distinct neural activity across hunger, feeding, and satiety states. However, the functional and evolutionary conservation of relevant neural circuits remain unclear. Using integrative transcriptomics of zebrafish and mouse LH, we identify conserved cellular clusters with shared molecular markers, particularly within GABAergic neurons. We highlight a conserved GABAergic population expressing tachykinin and growth hormone receptors, which is responsive to food cues and modulated by hunger and feeding states. This cluster may mediate acute appetite-enhancing effects of growth hormone. In both species, feeding elevates growth hormone receptor and tachykinin expression and activates these neurons, while human growth hormone increases their activity and food intake in zebrafish. These findings suggest a conserved neural mechanism by which metabolic hormones influence feeding behavior. Our comparative LH atlas highlights the evolutionary biology of appetite regulation and the integration of hormonal and neural signals driving energy homeostasis.

neuroscience↗

bioRxiv2025

Multiplexed profiling of transcriptional regulators in plant cells

Transcriptional regulators play key roles in plant growth, development, and environmental responses; however, understanding how their regulatory activity is encoded at the protein level has been hindered by a lack of multiplexed large-scale methods to characterize protein libraries in planta. Here, we present ENTRAP-seq (Enrichment of Nuclear Trans-elements Reporter Assay in Plants), a high-throughput method that introduces protein-coding libraries into plant cells to drive a nuclear magnetic sorting-based reporter, enabling multiplexed measurement of regulatory activity from thousands of protein variants. Using ENTRAP-seq and machine learning, we screened 1,495 plant viruses and identified hundreds of novel putative transcriptional regulatory domains found in structural proteins and enzymes not associated with gene regulation. In addition, we combined ENTRAP-seq with machine-guided design to engineer the activity of a plant transcription factor in a semi-rational fashion. Our findings demonstrate how scalable protein function assays deployed in planta will enable the characterization of natural and synthetic coding diversity in plants.

plant biology↗

bioRxiv2025

Accelerated evolution of whole gene clusters by an engineered lytic phage system in E. coli

Directed evolution excels at optimizing individual proteins, but simultaneous evolution of multiple genes remains a significant challenge. Here, we establish a robust phage-based system for accelerated evolution of large gene clusters of up to 39 kilobases. Lytic Selection and Evolution (LySE) selectively replicates and mutagenizes the target gene cluster, carried on a phagemid through alternating cycles of lysis and transduction in Escherichia coli. We engineered a hypermutagenic T7 DNA polymerase (T7 DNAP) that increases mutation rates of the replicating phagemid 7,000-fold during the lytic cycle. We further optimized the mutational spectrum by fusing the T7 DNAP to a dual adenine-cytosine deaminase to install all possible transition mutations at similar frequencies. LySE-mediated transduction enables selection for desired metabolic functions by coupling gene cluster expression to host fitness, while eliminating genomic off-target mutations by refreshing the host in each cycle. Using LySE, we evolved a 25-fold increase in tigecycline resistance in 5 cycles, and a 50.9% increase in end-point biomass of a bacterial strain that utilizes the PET monomer, ethylene glycol, as its sole carbon source.

synthetic biology↗