I developed computational pipelines and analyses to map transcription initiation and chromatin structure in non-model organisms. This page presents workflows, results, and code developed for P. infestans.
Overview of the Unique Skillset I Have Gained from Working in P. infestans
Working with Phytophthora infestans was both a challenge and an adventure. Unlike current researchers studying humans, who can simply select a ready-made reference genome from a database, I had no such luxury. The reference genome and annotation files I needed weren’t available in the standard repositories used by most bioinformatics tools. This meant I had to dig deeper: reading documentation, examining source code, and piecing together how each package handled genomic data. Step by step, I learned to transform my genome files into the precise data structures those tools required. Only after this groundwork could I begin the analyses themselves. Working with P. infestans strengthened not only my technical skills but also my resilience and creativity, growth that would have been unlikely in more established systems.
A brief summary of results
5′-prime MACE Sequencing (Chapter 1)
Generated genome-wide maps of transcription start sites (TSSs) and transcription start regions (TSRs) in Phytophthora infestans.
Found that sense transcripts are approximately ten times more abundant than antisense transcripts.
Identified developmentally regulated differences in sense and antisense transcription initiation.
Demonstrated that 5′-MACE sequencing improves gene model accuracy and highlights tissue-specific transcriptional differences from the same gene locus.
Discovered two novel CG-rich promoter motifs and three INR+FPR-like motifs, all associated with enhanced transcription initiation and differential gene expression.
Nucleosome Occupancy Analysis (Chapter 2)
Conducted the first comprehensive study of nucleosome occupancy across developmental stages in a Phytophthora species (P. infestans).
Found that nucleosome density correlates variably with gene density, reflecting the complex, bipartite genome architecture of P. infestans.
Identified a nucleosome-free region (NFR) upstream of transcription start regions.
Detected a +1 nucleosome downstream of some transcription start regions, with variable strength across developmental stages.
Examples of my code
The documents contain the code used to perform the analyses presented in my dissertation. Because my advisor had limited experience in computational research, I developed this work largely independently. On occasion, I sought guidance from package developers through GitHub or from administrators of the high-performance computing cluster.