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Biology subjects

Odell, A.

Publications and source records attributed to Odell, A..

2 recordsLinked to original sources

Environment-Aware DNA Language Model for Stress-Responsive Genomic Prioritization in Maize

Abiotic stresses such as heat and drought severely reduce maize productivity, yet identifying genomic regions that confer stress resilience remains a challenge. Inspired by advances in Large Language Models (LLMs), Genomic Foundation Models (GFMs) have recently emerged as a promising approach for capturing regulatory patterns through large-scale pre-training on DNA sequences. However, their application to plant stress-response analysis remains unexplored. This study presents an environment-aware DNA-LLM that adapts AgroNT, a transformer-based GFM pre-trained on diverse plant genomes, by incorporating stress-specific prompt tokens. Through parameter-efficient fine-tuning, the model learns stress-conditioned sequence representations that form distinct clusters in the embedding space across environmental contexts. By combining stress-induced shifts in these sequence representations relative to control conditions with transformer attention patterns, we prioritized putative heat- and drought-responsive genomic regions associated with grain yield in the Genomes-to-Fields (G2F) panel. Prioritized regions were supported by spatiotemporal differential gene-expression evidence and overlap with stress-associated quantitative trait loci. They were further characterized through transcription-factor family analysis and regulatory motif enrichment. Attention-guided analysis additionally identified stress-associated motifs enriched within model-emphasized sequence regions. Overall, the prioritized loci were proximal to genes involved in transcriptional regulation, signaling, and metabolic pathways relevant to abiotic-stress adaptation, demonstrating the potential of stress-conditioned transformer-based sequence modeling for environment-aware genome-to-phenome analysis.

genomics↗

Post-meiotic mechanism of facultative parthenogenesis in gonochoristic whiptail lizard species.

Facultative parthenogenesis (FP) has historically been regarded as rare in vertebrates, but in recent years incidences have been reported in a growing list of fish, reptile, and bird species. Despite the increasing interest in the phenomenon, the underlying mechanism and evolutionary implications have remained unclear. A common finding across many incidences of FP is a high degree of homozygosity at microsatellite loci. This has led to the proposal that first or second polar body fusion following the meiotic divisions restores diploidy and thereby mimics fertilization. Here we show that FP occurring in the gonochoristic Aspidoscelis species A. marmoratus and A. arizonae results in genome-wide homozygosity, an observation inconsistent with polar body fusion as the underlying mechanism of restoration. Instead, a high-quality reference genome for A. marmoratus and analysis of whole-genome sequencing from multiple FP and control animals reveals that a post-meiotic mechanism gives rise to homozygous animals from haploid, unfertilized oocytes. Contrary to the widely held belief that females need to be isolated from males to undergo FP, females housed with conspecific and heterospecific males produced unfertilized eggs that underwent spontaneous development. In addition, a mixture of offspring arising from fertilized eggs and parthenogenetic development was observed to arise from a single clutch. Strikingly, our data support a mechanism for facultative parthenogenesis that removes all heterozygosity in a single generation. Complete homozygosity exposes the genetic load and explains the high rate of congenital malformations and embryonic mortality associated with FP in many species. Conversely, FP constitutes strong purifying selection as non-functional alleles of all essential genes are purged in a single generation.

genomics↗