Biology subjects

Oleksyk, T. K.

Publications and source records attributed to Oleksyk, T. K..

8 recordsLinked to original sources

bioRxiv2026

A draft de novo assembly of Diadema antillarum, a keystone herbivore of the Caribbean reefs

We generated the first reference-level nuclear genome assembly of the keystone Caribbean long-spined black sea urchin species, Diadema antillarum (Philippi, 1845). Using whole-genome sequencing data from PacBio HiFi, Oxford Nanopore, and Illumina platforms, we employed multiple assembly strategies to generate a high-quality, near-complete genome. The final assembly spans 1.73 Gbp, consists of 2,964 scaffolds, and has an N50 of 1.56 Mbp. BUSCO analysis (metazoa_odb10) indicates 98.4% completeness. The genome displays a heterozygosity rate of 2.52% and contains 42.85% repetitive elements, of which 29.96% are unclassified. Coverage analysis reveals that while most of the genome was assembled at 11x depth, certain regions exhibit up to 530x coverage. Notably, regions exceeding 33x coverage account for 30.53% of the repetitive content, suggesting localized expansion of repeats. Duplication analysis of the assembled contigs shows that approximately 66% of contigs have duplicated, which supports segmental genome duplication in the past, and is further evidenced by the moderate level of heterozygosity of the assembly. While these characteristics contribute to the complexity of the genome, they do not diminish the quality of our assembly. Despite this complexity, our assembly maintains high completeness and contiguity. Our assembly provides a valuable resource for future genetic studies and serves as a critical framework for conservation, monitoring, and restoration of D. antillarum populations across the Caribbean.

genetics↗

bioRxiv2026

Leveraging a hybrid cross-disciplinary training model to accelerate global bioinformatics capacity

Disparities in formal bioinformatics training exacerbate the global skills gap, impeding the democratized application of advanced genomic technologies. To bridge this divide, we introduce a scalable, hybrid training framework designed to rapidly accelerate regional bioinformatics capacity. We exemplify this approach through the Eastern European Bioinformatics and Genomics (EEBG) workshop series -- a cross-disciplinary initiative that pairs international faculty with local institutions to deliver modular, hands-on curricula. Functioning as a structured knowledge-transfer pipeline, the series has catalyzed a sustainable educational ecosystem, evidenced by the establishment of multiple independent summer schools across the region. The assessment of the 2025 EEBG workshop in Krakow, Poland, validates the models viability; participant metrics confirm high efficacy in skill acquisition (mean satisfaction: 4.4/5.0) and community building. Crucially, the hybrid delivery mode dismantled geographic barriers, serving as a vital mechanism for maintaining scientific continuity for researchers facing displacement and crisis. Synthesizing these outcomes, we define the core features of a replicable blueprint for scientific readiness in resource-constrained environments. We conclude by presenting a strategic roadmap -- organized around infrastructure standardization, governance sustainability, and geographical expansion -- for adapting this regional proof-of-concept into a global export-ready model, offering a critical path toward ensuring universal access to genomic innovation.

scientific communication and education↗

bioRxiv2024

The First Comprehensive Description of the Platelet Single Cell Transcriptome

Platelets are derived from megakaryocytes, either in peripheral or pulmonic circulation. The transcriptome of megakaryocytes has been studied, while the platelet transcriptome is thought to be a reflection of their parent cells; it has not yet been investigated. Although platelets lack nuclei, they inherit RNA from their parent megakaryocytes, while only about 10% of them are believed to contain enough RNA for meaningful analysis. This study explores the potential of single-cell RNA sequencing to analyze the platelet transcriptome, aiming to expand our understanding of platelets beyond their traditional role in coagulation. Using acridine orange staining and antibody-based sequencing, we successfully sequenced RNA from seven healthy donors. Results revealed significant heterogeneity in gene expression, with common platelet markers, such as ITGA2B and GP1B, being less abundant than expected. Interestingly, immune markers associated with lung megakaryocytes were not strongly represented in peripheral platelets. Comparison with current algorithms for cell identification suggests that platelets are often misclassified as other blood cell types, highlighting limitations of existing pipelines in platelet annotation. This misclassification may have led to misrepresentation of platelet transcriptomics in previous studies. These findings underscore the need for tailored sequencing methods to accurately profile platelets and set the foundation for further exploration of platelet biology and immune function, potentially opening avenues for therapeutic interventions in immune modulation, drug delivery, and the use of platelets as disease biomarkers in cancer and other conditions. Key PointsPlatelet single cell sequencing can be implemented with appropriate technical refinements to ensure optimal isolation without exogenous activation. In comparison to bulk sequencing techniques, single cell analysis affords the ability to exclude contaminating cells enabling examination of the authentic platelet transcriptome. This is critically important as contaminating cells contain far more RNA ultimately skewing results of transcriptomic analysis. Most platelets do not contain significant levels of commonly expected transcripts such as ITGA2B, GP1B, TREML1. In the context of recent data, our single cell transcriptomic data supports the intradividual and interindividual heterogeneity of the platelet transcriptome. The lung megakaryocyte signature is not disguisable in peripheral platelets. Further studies are needed to understand sources of RNA within platelets and the impact of the platelet microenvironment. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/618506v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@556339org.highwire.dtl.DTLVardef@1e543c4org.highwire.dtl.DTLVardef@c41cb5org.highwire.dtl.DTLVardef@138d779_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOVisual abstractC_FLOATNO C_FIG

bioinformatics↗

bioRxiv2024

PopGenPlayground: a population genomics analysis pipeline

BackgroundPopulation genomic projects are essential in the current drive to map the genome diversity of human populations across the globe. Various barriers persist hindering these efforts, and the lack of bioinformatic expertise and reproducible standardized population-scale analysis is one of the major challenges limiting their discovery potential. Scalable, automated, user-friendly pipelines can help researchers with minimum programming skills to tackle these issues without extensive training. ResultsPopGenPlayground (PGP), is a streamlined, single-command computation pipeline designed for human population genomics analysis based on Snakemake workflow management system. Developed to automate secondary analysis of a previously published national genome project, it leverages the publicly available genomic databases for comparative analysis and annotation of variant calls. ConclusionsPGP presents a multi-platform robust population analysis pipeline, that reduces the time and the expertise levels to perform the main core of population analysis for a national genome project. PGP provides a comprehensive secondary analysis tool and can be used to perform analysis on a personal computer or using a remote high-performance computing platform.

bioinformatics↗

bioRxiv2024

ROUA Database: 300 Human Genomes from the border of Ukraine and Romania

We present a multi-layered data source (ROUA Database) providing the results of Whole Genome Sequencing of two human populations in the Carpathian Mountains region, specifically Ukraines Transcarpathia and Romanias Satu Mare and Baia Mare provinces, areas previously underexplored in population genomics. The database contains the raw and annotated files of the whole genome sequences from 300 individuals from these regions, including annotations of common and unique genetic variants following a sampling protocol designed to capture the genetic diversity of Ukrainians and Romanians, including minority groups like Wallachians and Roma. The data is hosted on a dedicated web resource. We provide information on how to access to results of primary and secondary analysis of the data, including comparative analysis with previously published populations from Ukraine, and populations from International Genome Sample Resource and Human Genome Diversity Project. The free research access to this database is contributing to growing understanding of human genetic diversity in Central Europe. This effort emphasizes the potential for reuse of the generated data, advocating for open access to support future research in genomics, bioinformatics, and personalized medicine.

genomics↗

bioRxiv2022

The first complete mitochondrial genome of Diadema antillarum (Diadematoida, Diadematidae)

The mitochondrial genome of the long-spined black sea urchin, Diadema antillarum, was sequenced using Illumina next generation sequencing technology. The complete mitogenome is 15,708 bp in length, containing 2 rRNA, 22 tRNA and 13 protein-coding genes, plus a non-coding control region of 133 bp. The nucleotide composition includes 18.37% G, 23.79% C, 26.84% A and 30.99% T. The A + T bias is 57.84%. Phylogenetic analysis based on 12 complete mitochondrial genomes of sea urchins including four species of the family Diadematidae supported familial monophyly, however the two Diadema species, D. antillarum and D. setosum were not recovered as sister taxa.

genomics↗

bioRxiv2020

Genome Diversity in Ukraine

The main goal of this collaborative effort is to provide genome wide data for the previously underrepresented population in Eastern Europe, and to provide cross-validation of the data from genome sequences and genotypes of the same individuals acquired by different technologies. We collected 97 genome-grade DNA samples from consented individuals representing major regions of Ukraine that were consented for the public data release. DNBSEQ-G50 sequences, and genotypes by an Illumina GWAS chip were cross-validated on multiple samples, and additionally referenced to one sample that has been resequenced by Illumina NovaSeq6000 S4 at high coverage. The genome data has been searched for genomic variation represented in this population, and a number of variants have been reported: large structural variants, indels, CNVs, SNPs and microsatellites. This study provides the largest to-date survey of genetic variation in Ukraine, creating a public reference resource aiming to provide data for historic and medical research in a large understudied population. While most of the common variation is shared with other European populations, this survey of population variation contributes a number of novel SNPs and structural variants that have not been reported in the gnomAD/1KG databases representing global distribution of genomic variation. These endemic variants will become a valuable resource for designing future population and clinical studies, help address questions about ancestry and admixture, and will fill a missing place in the puzzle characterizing human population diversity in Eastern Europe. Our results indicate that genetic diversity of the Ukrainian population is uniquely shaped by the evolutionary and demographic forces, and cannot be ignored in the future genetic and biomedical studies. This data will contribute a wealth of new information bringing forth different risk and/or protective alleles. The newly discovered low frequency and local variants can be added to the current genotyping arrays for genome wide association studies, clinical trials, and in genome assessment of proliferating cancer cells.

genomics↗

bioRxiv2017

Innovative assembly strategy contributes to the understanding of evolution and conservation genetics of the critically endangered Solenodon paradoxus from the island of Hispaniola

Solenodons are insectivores living on the Caribbean islands, with few surviving related taxa. The genus occupies one of the most ancient branches among the placental mammals. The history, unique biology and adaptations of these enigmatic venomous species, can be greatly advanced given the availability of genome data, but the whole genome assembly for solenodons has never been previously performed, partially due to the difficulty in obtaining samples from the field. Island isolation has likely resulted in extreme homozygosity within the Hispaniolan solenodon (Solenodon paradoxus), thus we tested the performance of several assembly strategies for performance with genetically impoverished species genomes. The string-graph based assembly strategy seems a better choice compared to the conventional de Brujn graph approach, due to the high levels of homozygosity, which is often a hallmark of endemic or endangered species. A consensus reference genome was assembled from sequences of five individuals from the southern subspecies (S. p. woodi). In addition, we obtained one additional sequence of the northern subspecies (S. p. paradoxus). The resulting genome assemblies were compared to each other, and annotated for genes, with a specific emphasis on the venomous genes, repeats, variable microsatellite loci and other genomic variants. Phylogenetic positioning and selection signatures were inferred based on 4,416 single copy orthologs from 10 other mammals. Patterns of SNP variation allowed us to infer population demography, which indicated a subspecies split within the Hispaniolan solenodon at least 300 Kya.

evolutionary biology↗