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Semwal, A.

Publications and source records attributed to Semwal, A..

2 recordsLinked to original sources

Tranquillyzer: A Flexible Neural Network Framework for Structural Annotation and Demultiplexing of Long-Read Transcriptomes

Long-read single-cell RNA sequencing using platforms such as Oxford Nanopore Technologies (ONT) enables full-length transcriptome profiling at single-cell resolution. However, high sequencing error rates, diverse library architectures, and increasing dataset scale introduce major challenges for accurately identifying cell barcodes (CBCs) and unique molecular identifiers (UMIs) - key prerequisites for reliable demultiplexing and deduplication, respectively. Existing pipelines rely on hard-coded heuristics or local transition rules that cannot fully capture this broader structural context and often fail to robustly interpret reads with indel-induced shifts, truncated segments, or non-canonical element ordering. We introduce Tranquillyzer (TRANscript QUantification In Long reads-anaLYZER), a flexible, architecture-aware deep learning framework for processing long-read single-cell RNA-seq data. Tranquillyzer employs a hybrid neural network architecture and a global, context-aware design, and enables precise identification of structural elements - even when elements are shifted, partially degraded, or repeated due to sequencing noise or library construction variability. In addition to supporting established single-cell protocols, Tranquillyzer accommodates custom library formats through rapid, one-time model training on user-defined label schemas, typically completed within a few hours on standard GPUs. Additional features such as scalability across large datasets and comprehensive visualization capabilities further position Tranquillyzer as a flexible and scalable framework solution for processing long-read single-cell transcriptomic datasets.

bioinformatics↗

Identification of two β-cell subtypes by 7 independent criteria

Despite the recent explosion in surveys of cell-type heterogeneity, the mechanisms that specify and stabilize highly related cell subtypes remain poorly understood. Here, focusing initially on exploring quantitative histone mark heterogeneity, we identify two major sub-types of pancreatic {beta}-cells ({beta}HI and {beta}LO). {beta}HI and {beta}LO cells differ in their size, morphology, cytosolic and nuclear ultrastructure, transcriptional output, epigenomes, cell surface marker, and function. Importantly, {beta}HI and {beta}LO cells can be FACS separated live into CD24+ ({beta}HI) and CD24- ({beta}LO) fractions. From an epigenetic viewpoint, {beta}HI-cells exhibit [~]4-fold higher levels of H3K27me3, more compacted chromatin, and distinct chromatin organization that associates with a specific pattern of transcriptional output. Functionally, {beta}HI cells have increased mitochondrial mass, activity, and insulin secretion both in vivo and ex vivo. Critically, Eed and Jmjd3 loss-of-function studies demonstrate that H3K27me3 dosage is a significant regulator of {beta}HI / {beta}LO cell ratio in vivo, yielding some of the first-ever specific models of {beta}-cell sub-type distortion. {beta}HI and {beta}LO sub-types are conserved in humans with {beta}HI-cells enriched in human Type-2 diabetes. These data identify two novel and fundamentally distinct {beta}-cell subtypes and identify epigenetic dosage as a novel regulator of {beta}-cell subtype specification and heterogeneity. HighlightsO_LIQuantitative H3K27me3 heterogeneity reveals 2 common {beta}-cell subtypes C_LIO_LI{beta}HI and {beta}LO cells are stably distinct by 7 independent sets of parameters C_LIO_LIH3K27me3 dosage controls {beta}HI / {beta}LO ratio in vivo C_LIO_LI{beta}HI and {beta}LO cells are conserved in humans and enriched in Type-2 diabetes C_LI

cell biology↗