Biology subjects

Albert, E.

Publications and source records attributed to Albert, E..

6 recordsLinked to original sources

bioRxiv2026

HLA alleles and haplotype distribution across Russian population groups

HLA loci are highly polymorphic genome regions, with allele frequencies varying significantly across different populations. Population HLA frequency databases may contain biases and make cross-study comparison complicated due to varying data curation protocols, genotyping methodologies, resolution, and inconsistencies in the selection criteria for population samples. This study presents HLA allele frequencies of class I (HLA-A, -B, -C) and class II (HLA-DRB1, -DQB1, -DQA1) as well as their combined haplotypes obtained from over 18,000 whole genome sequencing samples of the Russian population. Cohort was stratified based on PCA and admixture components providing frequencies for 14 different ethnic groups. For 12 groups cohort size allowed us to reach average saturation of 96% of allele frequencies in groups. Moreover, we demonstrated the utility of composed statistics for disease populational study using type 1 diabetes (T1D) as an example. Populations with similar aggregated genetic risk for T1D demonstrated substantial differences in frequencies of risk and protective HLA alleles. Obtained frequency data was made publicly available through the Allele Frequency Net Database improving previously sparse coverage in HLA frequencies data for east Europe and north Asia regions.

genetics↗

bioRxiv2026

Systematic analysis of insertions signature in gnomAD revealed large set of novel processed pseudogenes

Pseudogenes are non-functional copies of protein-coding genes that arise through genomic duplication or retrotransposition. Processed pseudogenes (PPs) is the most abundant class of pseudogenes, which is generated via mRNA reverse transcription and subsequent cDNA integration. Presence of PPs complicates the analysis of short read sequencing data due to high similarity with parental gene and frequent absence from reference genome. Here we demonstrate that the presence of non-reference (absent from reference genome) PPs leads to the very distinctive artefact of germline variant calling - long insertions on exon-intron boundaries, which sequences could be mapped to other exons of the same gene. We showed that by detecting these artifacts it is possible to identify non-reference PPs existence based on the cohort summary statistics without analysing sample-level data. We used identified signature of PPs presence to systematically mine the gnomAD database which currently contains over 70,000 whole-genome and over 700,000 exome samples to describe novel non-reference PPs. Our approach uncovered 1498 non-reference PPs of which 1268 were novel and absent in the latest GENCODE release. This resource enhances the accuracy of variant interpretation and contributes to a deeper understanding of pseudogenes diversity across human populations.

genomics↗

bioRxiv2025

New resistance to bacterial wilt in heat-stressed tomato is revealed by two-reference Genome Wide Association

Bacterial wilt, caused by bacterial strains of the Ralstonia solanacearum species complex, is one of the most harmful diseases striking many crops including tomato. Its spread is dependent upon temperature and humidity, which are expected to fluctuate strongly due to climate change. Previous results have highlighted that temperature elevation led to an increase in disease severity in commercial cultivars, whose resistance is quantitative and mostly relies on the Quantitative Trait Loci (QTL) bwr-6 and bwr-12. In this study, we focused on temperature-dependent quantitative disease resistance (QDR) to bacterial wilt with the aim to unravel new resistance mechanisms that remain efficient at higher temperatures. For this purpose, a new panel of 189 accessions composed of tomato wild relatives, was assembled and sequenced thus creating a unique genomic resource. Its response to the Ralstonia pseudosolanacearum strain GMI1000 from three- to ten-days post-inoculation at 28{degrees}C and 32{degrees}C was explored. To discover the genetic basis underlying the responses of the panel, Genome-Wide Association (GWA) studies were conducted using the disease symptom scores recorded daily and monitored throughout the kinetics of the infection. To improve QTL detection, we have proposed a new approach using two reference genomes from within the panel. By correcting part of a single reference genome, especially when the only reference genome is a cultivar, this approach may be considered an alternative to pangenomic studies. As panel sequencing was highly resolutive, QTL positions allowed the identification of 44 candidate genes, which seemed to follow a temporal dynamic of activation after pathogen inoculation. Interestingly, no candidate genes were found to be common between the two phenotyping temperatures, highlighting the importance of the experimental design in addressing this type of question. Most of our quantitative disease resistance candidate genes belong to gene families described as being involved in immunity. Moreover, a significant proportion appears to be expressed in roots where bacterial infection occurs. Among them, two candidates are closely linked to the genomic positions of the bwr-6 and bwr-12 QTLs, the main QTLs of bacterial wilt Quantitative Disease Resistance (QDR) studied whose mechanisms of action are still unknown. Author summaryBacterial wilt is a plant disease that affects more than 200 crop species (including tomato, potato and banana) leading to high yield losses. The most efficient way to deal with this disease is still the use of genetic resistance. However, previous studies have shown that numerous sources of resistance are negatively affected when plants face heat stress, which is alarming in a context of global warming. In this study, we have developed a new approach for discovering candidate genes in tomato capable of conferring thermostable resistance to bacterial wilt. Forty-four genes were sequentially detected over time, reflecting different temporal dynamics of induction after inoculation. Even if none were found to be common between the two temperatures, available information on their transcriptional regulation in roots and their involvement in immune processes confirms their relevance. Finally, we provide a short list of the candidate genes identified, some of which are currently undergoing functional validation and will be used in breeding programs to help overcome epidemics in future years.

genetics↗

bioRxiv2024

Sanger validation of WGS variants - when to?

With the development of Next-Generation Sequencing (NGS) technologies it became possible to simultaneously analyze millions of variants. Despite the quality improvement it is generally still required to confirm the variants before reporting. However, in recent years the dominant idea is that one could define the quality thresholds for "high quality" variants which do not require orthogonal validation. Despite that, no works to date report the concordance between variants from whole genome sequencing and their gold-standard Sanger validation. In this study we analyzed the concordance for 1756 WGS variants in order to establish the appropriate thresholds for high-quality variants filtering. Resulting thresholds allowed us to drastically reduce the number of variants which require validation, to 5,6% and 1.2% of the initial set for caller-agnostic thresholds and caller-dependent QUAL threshold respectively.

genomics↗

bioRxiv2024

Comparative framework and adaptation of ACME HS approach to single cell isolation from fresh-frozen endocrine tissues

Current scRNA-seq studies of solid tissues mostly rely on enzymatic dissociation of fresh samples or the fallback on nuclei isolation from frozen or partially fixed samples. However, due to the complex tissue organization or cell fragility, it could be challenging to apply these approaches to the sensitive endocrine tissues. That is, dissociating intact cells from such problematic fresh-frozen samples routinely collected by biobanks remains challenging. In this study, we adapted the acetic-methanol dissociation method - ACME High Salt (ACME HS) to effectively isolate intact single cells from fresh-frozen endocrine tumor samples, including adrenal gland neoplasms, thyroid carcinomas, and pituitary neuroendocrine tumors. We compared the ability of enzymatic, ACME HS, and nuclear isolation methods to preserve the integrity of major cell types and gene expression across 41 tissue samples of different origins. We demonstrated that ACME HS simultaneously dissociates and fixes cells, thus preserving morphology and a high RNA integrity number in problematic cell types. This finding renders the ACME HS dissociation method a valuable alternative in scRNA-seq protocols for challenging tissues where obtaining live cell suspension is difficult or impossible.

genomics↗

bioRxiv2023

Dark side of the honeymoon: reconstructing the Asian x European rose breeding history through the lens of genomics

O_LIRoses hold significant symbolic value in Western cultural heritage, often serving as a symbol of love and romance. Despite their ancient cultivation, the appreciation for the phenotypic diversity of roses emerged relatively recently, notably during the 19th century. This period is characterized by a remarkable expansion in the number of varieties, from around 100 to over 8,000, representing a golden age for roses. C_LIO_LITo trace the history of rose breeding in Europe and unveil genetic changes during this period, we gathered phenotypic and genetic data from 204 accessions. These included botanical roses and varieties cultivated between 1800 and 1910. Whole-genome sequences from 32 accessions were also included. C_LIO_LIOur analysis revealed a temporal shift in the genetic makeup, transitioning from a historical European to a near-Asian genetic background within a few generations. This shift was accompanied by a notable reduction in genetic diversity, attributed to the backcrossing with the less diverse Asian genepool, plus some genomic signatures of selection. C_LIO_LIWe have generated the largest GWAS catalog for rose to date, offering a valuable resource for future breeding initiatives. We emphasize the critical importance of preserving ancient rose collections to safeguard diversity and ensure a sustainable breeding for the long term. C_LI

genomics↗