Biology subjects

Grinevich, D.

Publications and source records attributed to Grinevich, D..

4 recordsLinked to original sources

bioRxiv2025

Telomeric assemblies of Paracoccidioides genomes

Paracoccidioides is a genus of dimorphic fungal pathogens endemic to Latin America. We generated long-read de novo assemblies for 11 isolates representing four species of the brasiliensis complex (P. brasiliensis, P. americana, P. restrepiensis, P. venezuelensis) and P. lutzii. These include the first complete telomere-to-telomere assemblies for P. brasiliensis (Pb18) and P. americana (Pb03), each with five chromosomes. Comparative analyses revealed chromosomal fusion and fission events distinguishing P. brasiliensis and P. americana, and a 90 kb tandem duplication in P. americana containing siderophore biosynthesis genes (sid1, sid3, sid4), a cluster of putative virulence factors. Mitochondrial genomes showed conserved gene order but a phylogenetic topology inconsistent with the nuclear tree, suggesting mitochondrial introgression between P. lutzii and P. venezuelensis. RNA transposable elements were enriched near telomeres, correlated with genome size, and most abundant in P. lutzii. These assemblies provide key resources for understanding genome evolution and introgression in Paracoccidioides. SIGNIFICANCESpecies of Paracoccidioides cause paracoccidioidomycosis, a systemic mycosis that remains a major public health problem in Latin America. Despite their clinical importance, genome evolution across the genus is poorly understood owing to the lack of complete reference assemblies. Here, we present the first telomere-to-telomere reference genomes for P. brasiliensis and P. americana, enabling a comprehensive comparison of chromosomal structure across the genus. Our analyses reveal that the nuclear genome is highly dynamic and shaped by large-scale rearrangements and structural variants, including the duplication of a siderophore biosynthesis-related gene cluster linked to virulence. In contrast, the mitochondrial genome is structurally conserved but shows introgression between species, revealing hidden evolutionary exchange. Together, these genomic resources redefine our understanding of Paracoccidioides evolution and provide a foundation for advances in molecular diagnostics, epidemiological surveillance, and studies of fungal pathogenicity.

microbiology↗

bioRxiv2025

FLYWCH transcription factors act in a LIN-42/Period autoregulatory loop during gonad migration in C. elegans

Development must be coordinated across body systems but must also accommodate cell-type-specific processes. We discovered that the gene regulatory circuit controlling developmental timing in the Caenorhabditis elegans larval skin exhibits both points of convergence and divergence with the regulatory program governing the migration of the leader cell in gonad development, the distal tip cell (DTC). As a point of convergence, the conserved regulator of developmental timing, LIN-42/Period, peaks synchronously across cell types both during the L3 stage, when the DTC makes a turn in its normal migratory path, and the L4 stage in which the DTC normally continues straight ahead. We report that lin-42, like its ortholog period, autorepresses its own transcription. lin-42 is required cell-autonomously for proper pathfinding of the DTC; DTC-specific lin-42 RNAi causes the DTC to turn in the mid-L4 instead of continuing straight ahead. We identified the FLYWCH transcription factor FLH-1 as able to directly bind the lin-42a promoter. Using live-cell imaging, we show that flh-1; flh-2 double mutant DTCs have an aberrant turn in the mid-L4. These mutants derepress the L4 peak of lin-42 expression in a stage- and DTC-specific manner, and this derepression is itself lin-42-dependent. During the aberrant mid-L4 turn in flh-1; flh-2 mutants, the focal adhesion factor TLN-1 is repolarized in the direction of turning. These results reveal that bodywide developmental rhythms can be fine-tuned to integrate with specific organogenic processes. SUMMARY STATEMENTTo identify new transcriptional regulators of distal tip cell migration, a screen for C. elegans transcription factors that bind the promoter of the Period homolog lin-42, a conserved regulator of developmental timing, uncovers a pair of factors that redundantly prevent misdirected migration of the distal tip cell-the cell that guides gonadal development. Through phenotypic analysis of genetic mutants, RNAi knockdown, and live imaging, we found that these transcription factors create a cell-specific autoregulatory loop that controls lin-42 transcription and promotes directional migration by polarizing the focal adhesion protein TLN-1.

developmental biology↗

bioRxiv2023

Serovar-level Identification of Bacterial Foodborne Pathogens From Full-length 16S rRNA Gene Sequencing

The resolution of variation within species is critical for interpreting and acting on many microbial measurements. In the key foodborne pathogens Escherichia coli and Salmonella, the primary sub-species classification scheme used is serotyping: differentiating variants within these species by surface antigen profiles. Serotype prediction from whole-genome sequencing (WGS) of isolates is now seen as comparable or preferable to traditional laboratory methods where WGS is available. However, laboratory and WGS methods depend on an isolation step that is time-consuming and incompletely represents the sample when multiple strains are present. Community sequencing approaches that skip the isolation step are therefore of interest for pathogen surveillance. Here we evaluated the viability of amplicon sequencing of the full-length 16S rRNA gene for serotyping S. enterica and E. coli. We developed a novel algorithm for serotype prediction, implemented as an R package (Seroplacer), which takes as input full-length 16S rRNA gene sequences and outputs serovar predictions after phylogenetic placement into a reference phylogeny. We achieved over 89% accuracy in predicting Salmonella serotypes on in silico test data, and identified key pathogenic serovars of Salmonella and E. coli in isolate and environmental test samples. Although serotype prediction from 16S sequences is not as accurate as serotype prediction from WGS of isolates, the potential to identify dangerous serovars directly from amplicon sequencing of environmental samples is intriguing for pathogen surveillance. The capabilities developed here are also broadly relevant to other applications where intra-species variation and direct sequencing from environmental samples could be valuable.

microbiology↗

bioRxiv2020

Ultra-accurate Microbial Amplicon Sequencing with Synthetic Long Reads

Out of the many pathogenic bacterial species that are known, only a fraction are readily identifiable directly from a complex microbial community using standard next generation DNA sequencing technology. Long-read sequencing offers the potential to identify a wider range of species and to differentiate between strains within a species, but attaining sufficient accuracy in complex metagenomes remains a challenge. Here, we describe and analytically validate LoopSeq, a commercially-available synthetic long-read (SLR) sequencing technology that generates highly-accurate long reads from standard short reads. LoopSeq reads are sufficiently long and accurate to identify microbial genes and species directly from complex samples. LoopSeq applied to full-length 16S rRNA genes from known strains in a microbial community perfectly recovered the full diversity of full-length exact sequence variants in a known microbial community. Full-length LoopSeq reads had a per-base error rate of 0.005%, which exceeds the accuracy reported for other long-read sequencing technologies. 18S-ITS and genomic sequencing of fungal and bacterial isolates confirmed that LoopSeq sequencing maintains that accuracy for reads up to 6 kilobases in length. Analysis of rinsate from retail meat samples demonstrated that LoopSeq full-length 16S rRNA synthetic long-reads could accurately classify organisms down to the species level, and could differentiate between different strains within species identified by the CDC as potential foodborne pathogens. The order-of-magnitude improvement in both length and accuracy over standard Illumina amplicon sequencing achieved with LoopSeq enables accurate species-level and strain identification from complex and low-biomass microbiome samples. The ability to generate accurate and long microbiome sequencing reads using standard short read sequencers will accelerate the building of quality microbial sequence databases and removes a significant hurdle on the path to precision microbial genomics.Competing Interest StatementMichael Balamotis and Tuval Ben Yehezkel are employees of Loop Genomics, the vendor for the synthetic long-read sequencing technology analyzed in this manuscript.View Full Text

microbiology↗