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Genomics

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bioRxiv2019

A sorghum Practical Haplotype Graph facilitates genome-wide imputation and cost-effective genomic prediction

Successful management and utilization of increasingly large genomic datasets is essential for breeding programs to increase genetic gain and accelerate cultivar development. To help with data management and storage, we developed a sorghum Practical Haplotype Graph (PHG) pangenome database that stores all identified haplotypes and variant information for a given set of individuals. We developed two PHGs in sorghum, one with 24 individuals and another with 398 individuals, that reflect the diversity across genic regions of the sorghum genome. 24 founders of the Chibas sorghum breeding program were sequenced at low coverage (0.01x) and processed through the PHG to identify genome-wide variants. The PHG called SNPs with only 5.9% error at 0.01x coverage - only 3% lower than its accuracy when calling SNPs from 8x coverage sequence. Additionally, 207 progeny from the Chibas genomic selection (GS) training population were sequenced and processed through the PHG. Missing genotypes in the progeny were imputed from the parental haplotypes available in the PHG and used for genomic prediction. Mean prediction accuracies with PHG SNP calls range from 0.57-0.73 for different traits, and are similar to prediction accuracies obtained with genotyping-by-sequencing (GBS) or markers from sequencing targeted amplicons (rhAmpSeq). This study provides a proof of concept for using a sorghum PHG to call and impute SNPs from low-coverage sequence data and also shows that the PHG can unify genotype calls from different sequencing platforms. By reducing the amount of input sequence needed, the PHG has the potential to decrease the cost of genotyping for genomic selection, making GS more feasible and facilitating larger breeding populations that can capture maximum recombination. Our results demonstrate that the PHG is a useful research and breeding tool that can maintain variant information from a diverse group of taxa, store sequence data in a condensed but readily accessible format, unify genotypes from different genotyping methods, and provide a cost-effective option for genomic selection for any species.

genomics↗

bioRxiv2019

Genome assembly of the common pheasant Phasianus colchicus, a model for speciation and ecological genomics

The common pheasant (Phasianus colchicus) in the order Galliformes and the family Phasianidae, has 30 subspecies distributed across its native range in the Palearctic realm and has been introduced to Europe, North America, and Australia. It is an important game bird often subjected to wildlife management as well as a model species to study speciation, biogeography and local adaptation. However, the genomic resources for the common pheasant are generally lacking. We sequenced a male individual of the subspecies torquatus of the common pheasant with the Illumina Hiseq platform. We obtained 94.88 Gb of usable sequences by filtering out low-quality reads of the raw data generated. This resulted in a 1.02 Gb final assembly, which equals the estimated genome size. BUSCO analysis using chicken as a model showed that 93.3% of genes were complete. The contig N50 and scaffold N50 sizes were 178 kb and 10.2 Mb, respectively. All these indicate that we obtained a high-quality genome assembly. We annotated 16,485 protein-coding genes and 123.3 Mb (12.05 % of the genome) of repetitive sequences by ab initio and homology-based prediction. Furthermore, we applied a RAD-sequencing approach for another 45 individuals of seven representative subspecies in China and identified 4,376,351 novel single nucleotide polymorphism (SNPs) markers. Using this unprecedented dataset, we uncover the geographic population structure and genetic introgression among common pheasants in China. Our results provide the first high-quality reference genome for the common pheasant and a valuable genome-wide SNP database for studying population genomics and demographic history.

genomics↗

bioRxiv2026

Diversity and Genomic Organization of Non-B DNA Motifs in Haplotype-Resolved Human Genome Assemblies

Long-read sequencing and telomere-to-telomere genome assemblies now enable the exploration of previously inaccessible repetitive and structurally complex regions of the human genome. Using 130 haplotype-resolved genome assemblies from 65 individuals across diverse populations, we systematically analyzed six major classes of non-B DNA motifs. By evaluating their biophysical stability, we distinguished structurally stable motifs from those forming unstable secondary structures and mapped their distribution across individuals and genomic contexts. Our work revealed significant variation at the population level in both motif abundance and predicted structural stability, uncovering previously unrecognized diversity in non-B DNA landscapes. Non-B DNA motifs exhibit notable, structure-specific enrichment in highly repetitive and evolutionarily dynamic regions that remain largely unresolved in short-read-based genomes, including centromeres, segmental duplications, structural variant breakpoints, and mobile element insertions. Our findings provide a refined view of the potential secondary-structure organization within repetitive regions of the human genome and highlight structural stability as a key factor shaping the distribution of non-B DNA motifs in regions linked to genome instability, evolution, and human variation.

genomics↗

bioRxiv2026

Revisiting the genome assembly of Lupinus species reveals differential diploidization after a shared whole-genome duplication

Accurate genome assemblies are essential for comparative genomics, yet Hi-C-guided scaffolding can introduce structural errors that misrepresent chromosome architecture and bias evolutionary inferences. Here, we identified pervasive scaffolding errors - including artificial fusions, internal inversions, and incomplete contig mounting - in two previously published Lupinus genomes (L. cosentinii and L. digitatus) using a segmentation method based on LTR retrotransposon density. We re-assembled both genomes, producing chromosome-level references of 472.7 Mb (16 chromosomes) and 427.2 Mb (21 chromosomes), with BUSCO completeness >98.5%. Synteny validation and re-application of LTR profiling confirmed that all prior errors were resolved. Using these corrected genomes together with four additional Lupinus species and two outgroup legumes, we investigated post-polyploid evolution. Synonymous substitution rate (Ks) analysis revealed a genus-specific whole-genome duplication (WGD) event (Ks = 0.17) shared by all six Lupinus species. The proportion of WGD-derived genes varied markedly, from 60% in L. digitatus to only 36% in L. mutabilis, indicating differential diploidization. While all species retained a core set of WGD duplicates enriched in cytoskeleton organization, ion transport, and defense responses, each exhibited lineage-specific functional trajectories: cell wall modification in L. cosentinii and L. digitatus, nitrogen metabolism in L. albus and L. angustifolius, flower development in L. luteus, and stress/lipid metabolism in L. mutabilis. Our corrected assemblies provide optimal references for Lupinus comparative genomics, and our findings demonstrate that a shared WGD event can lead to both conserved and highly divergent post-polyploid fates, likely underpinning adaptive diversification within the genus.

genomics↗

bioRxiv2026

Genome-wide mapping of Cas9-induced sister chromatid exchange across single and over 200 genomic targets

CRISPR/Cas9-induced DNA double-strand breaks (DSBs) are widely used for genome engineering, yet their capacity to provoke sister chromatid exchange (SCE) and associated genome instability remains incompletely understood, in part because exchanges between identical sister chromatids leave no sequence change and are invisible to conventional whole-genome sequencing. Using sci-L3-Strand-seq, a scalable single-cell template-strand sequencing platform for genome-wide SCE mapping, we quantified strand-switch events following targeted Cas9 cleavage. Cas9 targeting of a unique genomic locus led to strong local enrichment of SCE at the break site, reaching up to 41% in the same cell cycle and 17% in the subsequent division, indicating that DSB repair frequently engages non-local inter-sister repair. Extending the assay to 237 repetitive Alu targets using one Alu-specific sgRNA revealed mild and marginally statistically significant enrichment of on-target SCE across wild-type Cas9 and nickase variants (D10A and H840A). However, restricting analysis to a subset of cells with elevated SCE burden (>8 SCEs per cell) uncovered significant enrichment at programmed cut sites, suggesting that recombination at repetitive loci is conditionally engaged in highly recombinogenic cells. Reciprocal daughter-cell pair analysis further revealed large-scale structural alterations on chromosomes with induced SCEs and at SCE junctions, indicating that Cas9-induced SCEs do not universally reflect error-free homologous recombination. Disruption of DNA repair genes at the cut site, including LIG3, LIG4, XRCC1, and XRCC4, did not measurably alter SCE frequency per cell, consistent with delayed functional loss following editing and, in the case of essential genes such as LIG3, selection against disruptive alleles. Together, these findings demonstrate that Cas9-induced DSBs are potent local triggers of SCE at unique loci, while at repetitive regions SCE is more context-dependent and can be associated with structural alterations, highlighting the influence of lesion type and genomic context on recombination outcomes during genome editing.

genomics↗

bioRxiv2026

Species-rich and genomically diverse: comparative genomics reveals how fusions, fissions, and sex chromosomes have shaped beetle evolution

Chromosome evolution in animals reflects a balance between long-term conservation of ancestral linkage groups and lineage-specific chromosomal rearrangements that reshape genome structure. Beetles (Coleoptera), the most species-rich animal order, exhibit extensive diversity in karyotype, yet the extent to which their chromosomes retain deep ancestral structure remains unclear. Here, we analyzed 190 chromosome-level genome assemblies spanning 39 families and 16 superfamilies to characterize genome diversity, evaluate the conservation of ancestral linkage groups (Stevens elements), identify neo-sex chromosomes, and explore the role of repetitive elements in driving karyotypic change. Our results reveal that beetle genomes are highly diverse, varying substantially in genome size, chromosome number, GC content, and transposable element (TE) composition. Despite this diversity, Stevens elements appear conserved across much of the radiation, with several superfamilies maintaining strong chromosome synteny over more than 200 million years of evolution. In contrast, some clades, and specifically the leaf beetles (Chrysomelidae), have undergone extensive genomic changes including numerous chromosomal fusions and fissions and changes in genome size. Using synteny based approaches across beetles, we identified 37 species (approximately 19.5%) having patterns consistent with neo-sex chromosomes, a substantially higher frequency than previous estimates. These putative X-autosome fusions vary in complexity and age, often clustered within lineages that are prone to chromosomal instability. The ancestral X chromosome appears conserved for over 300 million years, with stable gene content and reduced TEs relative to autosomes. These findings help establish beetles as a promising system to uncover the evolutionary forces that maintain and disrupt ancestral linkage groups and drive the formation of neo-sex chromosomes.

genomics↗

bioRxiv2026

Chromosome-Level Nuclear Genome of Simulium vittatum Links Black Fly Cytogenetics to Genome Organization and Evolution

Black flies (Diptera: Simuliidae) are important vectors of pathogens affecting human and animal health, yet the absence of a chromosome-level nuclear reference genome has constrained molecular and evolutionary studies of the family. Here, we present the first chromosome-level nuclear genome and a developmental transcriptomic resource for the long-established IS-7 laboratory lineage of Simulium vittatum. Combining Oxford Nanopore long-read sequencing with Hi-C scaffolding, we assembled a 340.4-Mb genome, with 99.1% of the assembly resolved into three chromosome-length scaffolds (N50=104.8 Mb, BUSCO completeness 93.9%), consistent with the known 2n = 6 karyotype. Using the historically mapped molecular landmarks SVAT and SVEP, we assigned the two arms of chromosome III as IIIS and IIIL, respectively, linking sequence coordinates to the classical polytene chromosome map. Repetitive DNA comprises 46.48% of the assembly, including 29.68% unclassified repeats, and annotation identified 14,732 protein-coding genes and 16,417 transcripts. Integration with larval RNA-seq recovered the previously characterized silk gland proteins SGP-1-SGP-3 and resolved the expressed SGP-2 sequence despite a remaining discrepancy with the genomic sequence. This reference genome connects classical black fly cytogenetics with sequence-level analyses of genome organization, structural variation, and gene content, addressing a major genomic gap within Culicomorpha and providing a foundation for comparative studies of chromosome evolution, hematophagy, and vector biology across Simuliidae.

genomics↗

bioRxiv2026

Chromosome-level genome and caste transcriptomes for Africa's most widespread social wasp (Belonogaster juncea) reveal unexpected genomic diversity

Belonogaster is an African genus of primitively eusocial wasps. They are widespread and conspicuous across sub-Saharan Africa and yet are among the least studied groups of social wasps. Here, we present the first high-quality, chromosome-level genome assembly for a representative of this genus, Belonogaster juncea, complemented by an RNA-seq analysis of brain transcription among individuals representing reproductive and non-reproductive castes. The assembled genome spans 315.8 Mb with a scaffold N50 of 7.91 Mb. The annotation contained 15,159 protein-coding genes and 20,046 isoforms, with Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness of 98.0% for the genome and 97.8% for the annotation. Using this new assembly, we show that the B. juncea genome differs notably from other social wasp genomes: a single satellite repeat makes up a fifth of its chromosome-scale sequence, it has the highest putative chromosome number in a sequenced wasp genome to date, and it shows high levels of syntenic breaks. We find caste neuro-transcription differences between queens and workers, revealing 573 differentially expressed genes (341 worker biased, 232 queen biased), with significant overlap in caste-specific genes when compared to Polistes dominula and Liostenogaster flavolineata. This genomic resource provides a foundation for understanding the molecular mechanisms underlying primitive eusociality and social evolution in wasps, and opens up new research opportunities for a genus of little-studied insects from the Global South.

genomics↗

bioRxiv2015

Population genomics of the Anthropocene: urbanization is negatively associated with genome-wide variation in white-footed mouse populations

Urbanization results in pervasive habitat fragmentation and reduces standing genetic variation through bottlenecks and drift. Loss of genome-wide variation may ultimately reduce the evolutionary potential of animal populations experiencing rapidly changing conditions. In this study, we examined genome-wide variation among 23 white-footed mouse (Peromyscus leucopus) populations sampled along an urbanization gradient in the New York City metropolitan area. Genome-wide variation was estimated as a proxy for evolutionary potential using more than 10,000 SNP markers generated by ddRAD-Seq. We found that genome-wide variation is inversely related to urbanization as measured by percent impervious surface cover, and to a lesser extent, human population density. We also report that urbanization results in enhanced genome-wide differentiation between populations in cities. There was no pattern of isolation by distance among these populations, but an isolation by resistance model based on impervious surface significantly explained patterns of genetic differentiation. Isolation by environment modeling also indicated that urban populations deviate much more strongly from global allele frequencies than suburban or rural populations. This study is the first to examine loss of genome-wide SNP variation along an urban-to-rural gradient and quantify urbanization as a driver of population genomic patterns.

Evolutionary Biology↗

bioRxiv2015

Integrated Genome Browser: visual analytics platform for genomics

MotivationGenome browsers that support fast navigation and interactive visual analytics can help scientists achieve deeper insight into large-scale genomic data sets more quickly, thus accelerating the discovery process. Toward this end, we developed Integrated Genome Browser (IGB), a highly configurable, interactive and fast open source desktop genome browser.\n\nResultsHere we describe multiple updates to IGB, including all-new capability to display and interact with data from high-throughput sequencing experiments. To demonstrate, we describe example visualizations and analyses of data sets from RNA-Seq, ChIP-Seq, and bisulfite sequencing experiments. Understanding results from genome-scale experiments requires viewing the data in the context of reference genome annotations and other related data sets. To facilitate this, we enhanced IGBs ability to consume data from diverse sources, including Galaxy, Distributed Annotation, and IGB-specific Quickload servers. To support future visualization needs as new genome-scale assays enter wide use, we transformed the IGB codebase into a modular, extensible platform for developers to create and deploy all-new visualizations of genomic data.\n\nAvailabilityIGB is open source and is freely available from http://bioviz.org/igb.\n\nContactaloraine@uncc.edu

Bioinformatics↗

bioRxiv2017

Prophage genomics reveals patterns in phage genome organization and replication

Temperate phage genomes are highly variable mosaic collections of genes that infect a bacterial host, integrate into the hosts genome or replicate as low copy number plasmids, and are regulated to switch from the lysogenic to lytic cycles to generate new virions and escape their host. Genomes from most Bacterial phyla contain at least one or more prophages. We updated our PhiSpy algorithm to improve detection of prophages and to provide a web-based framework for PhiSpy. We have used this algorithm to identify 36,488 prophage regions from 11,941 bacterial genomes, including almost 600 prophages with no known homology to any proteins. Transfer RNA genes were abundant in the prophages, many of which alleviate the limits of translation efficiency due to host codon bias and presumably enable phages to surpass the normal capacity of the hosts translation machinery. We identified integrase genes in 15,765 prophages (43% of the prophages). The integrase was routinely located at either end of the integrated phage genome, and was used to orient and align prophage genomes to reveal their underlying organization. The conserved genome alignments of phages recapitulate early, middle, and late gene order in transcriptional control of phage genes, and demonstrate that gene order, presumably selected by transcription timing and/or coordination among functional modules has been stably conserved throughout phage evolution.

biochemistry↗

bioRxiv2019

Water lily (Nymphaea thermarum) draft genome reveals variable genomic signatures of ancient vascular cambium losses

For more than 225 million years, all seed plants were woody trees, shrubs, or vines (1-4). Shortly after the origin of angiosperms ~135 million years ago (MYA) (5), the Nymphaeales (water lilies) became one of the first lineages to deviate from their ancestral, woody habit by losing the vascular cambium (6), the meristematic population of cells that produces secondary xylem (wood) and phloem. Many of the genes and gene families that regulate differentiation of secondary tissues also regulate the differentiation of primary xylem and phloem (7-9), which are produced by apical meristems and retained in nearly all seed plants. Here we sequence and assemble a draft genome of the water lily Nymphaea thermarum, an emerging system for the study of early flowering plant evolution, and compare it to genomes from other cambium-bearing and cambium-less lineages (like monocots and Nelumbo). This reveals lineage-specific patterns of gene loss and divergence. Nymphaea is characterized by a significant contraction of the HD-ZIP III transcription factors, specifically loss of REVOLUTA, which influences cambial activity in other angiosperms. We also find the Nymphaea and monocot copies of cambium-associated CLE signaling peptides display unique substitutions at otherwise highly conserved amino acids. Nelumbo displays no obvious divergence in cambium-associated genes. The divergent genomic signatures of convergent vascular cambium loss reveals that even pleiotropic genes can exhibit unique divergence patterns in association with independent trait loss events. Our results shed light on the evolution of herbaceousness - one of the key biological innovations associated with the earliest phases of angiosperm evolution. Significance StatementFor ~225 million years, all seed plants were woody trees, shrubs, or vines. Shortly after the origin of flowering plants ~135 million years ago, Nymphaeales (water lilies) became one of the first seed plant lineages to become herbaceous through loss of the meristematic cell population known as the vascular cambium. We sequence and assemble the draft genome of the water lily Nymphaea thermarum, and compare it to genomes of other plants that have retained or lost the vascular cambium. By using both genome-wide and candidate-gene analysis, we find lineage-specific patterns of gene loss and divergence associated with cambium loss. Our reveal divergent genomic signatures of convergent trait loss in a system characterized by complex gene-trait relationships.

plant biology↗

bioRxiv2020

Single-Cell Analysis of the 3D Topologies of Genomic Loci Using Genome Architecture Mapping

Although each cell within an organism contains a nearly identical genome sequence, the three-dimensional (3D) packing of the genome varies among individual cells, influencing cell-type-specific gene expression. Genome Architecture Mapping (GAM) is the first genome-wide experimental method for capturing 3D proximities between any number of genomic loci without ligation. GAM overcomes several limitations of 3C-based methods by sequencing DNA from a large collection of thin sections sliced from individual nuclei. The GAM technique measures locus co-segregation, extracts radial positions, infers chromatin compaction, requires small numbers of cells, does not depend on ligation, and provides rich single-cell information. However, previous analyses of GAM data focused exclusively on population averages, neglecting the variation in 3D topology among individual cells. We present the first single-cell analysis of GAM data, demonstrating that the slices from individual cells reveal intercellular heterogeneity in chromosome conformation. By simultaneously clustering both slices and genomic loci, we identify topological variation among single cells, including differential compaction of cell cycle genes. We also develop a geometric model of the nucleus, allowing prediction of the 3D positions of each slice. Using GAM data from mouse embryonic stem cells, we make new discoveries about the structure of the major mammalian histone gene locus, which is incorporated into the Histone Locus Body (HLB), including structural fluctuations and putative causal molecular mechanisms. Our methods are packaged as SluiceBox, a toolkit for mining GAM data. Our approach represents a new method of investigating variation in 3D genome topology among individual cells across space and time.

bioinformatics↗

bioRxiv2020

CoalQC - Quality control while inferring demographic histories from genomic data: Application to forest tree genomes

Estimating demographic histories using genomic datasets has proven to be useful in addressing diverse evolutionary questions. Despite improvements in inference methods and availability of large genomic datasets, quality control steps to be performed prior to the use of sequentially Markovian coalescent (SMC) based methods remains understudied. While various filtering and masking steps have been used by previous studies, the rationale for such filtering and its consequences have not been assessed systematically. In this study, we have developed a reusable pipeline called "CoalQC", to investigate potential sources of bias (such as repeat regions, heterogeneous coverage, and callability). First, we demonstrate that genome assembly quality can affect the estimation of demographic history using the genomes of several species. We then use the CoalQC pipeline to evaluate how different repeat classes affect the inference of demographic history in the plant species Populus trichocarpa. Next, we assemble a draft genome by generating whole-genome sequencing data for Mesua ferrea (sampled from Western Ghats, India), a multipurpose forest plant distributed across tropical south-east Asia and use it as an example to evaluate several technical (sequencing technology, PSMC parameter settings) and biological aspects that need to be considered while comparing demographic histories. Finally, we collate the genomic datasets of 14 additional forest tree species to compare the temporal dynamics of Ne and find evidence of a strong bottleneck in all tropical forest plants during Mid-Pleistocene glaciations. Our findings suggest that quality control prior to the use of SMC based methods is important and needs to be standardised.

evolutionary biology↗

bioRxiv2020

Males that silence their father's genes: genomic imprinting of a complete haploid genome

Genetic conflict is considered a key driver in the evolution of new reproductive and sex determining systems. In particular, reproductive strategies with non-Mendelian inheritance, where parents do not contribute equally to the genetic makeup of their offspring. One of the most extraordinary examples of non-Mendelian inheritance is paternal genome elimination (PGE), a form of haplodiploidy which has evolved repeatedly across arthropods. Under PGE, males are diploid but only transmit maternally-inherited chromosomes to their offspring, while the paternal homologues are excluded from sperm. This asymmetric inheritance is thought to have evolved through an evolutionary arms race between paternal and maternal genomes over transmission to future generations. In several clades with PGE, such as the mealybugs (Hemiptera: Pseudococcidae), paternal chromosomes are not just eliminated from sperm, but also heterochromatinised early in development and thought to remain inactive. Such paternal genome silencing could alleviate genetic conflict between paternal alleles over transmission. However, it is unclear if paternal chromosomes are indeed genetically inert in both soma and germline. Here, we present a parent-of-origin allele-specific transcriptome analysis in male mealybugs. We show that expression is globally biased towards the maternal genome, but detect activity of paternal chromosomes in both somatic and reproductive tissues. Up to 70% of somatically-expressed genes are to some degree paternally-expressed. However, paternal genome expression is much more restricted in the testis, with only 20% of genes showing paternal contribution. Finally, we show that the patterns of parent-of-origin-specific gene expression are remarkably similar across genotypes and that those genes with biparental expression show elevated rates of molecular evolution. Our results provide the clearest example yet of genome-wide genomic imprinting (parent-of-origin specific gene expression) in insects. Furthermore, it enhances our understanding of PGE, which will aid future empirical tests of evolutionary theory regarding the origin of this unusual reproductive strategy.

evolutionary biology↗

bioRxiv2020

Comparative genomic analysis of Mycobacterium tuberculosis reveals evolution and genomic instability within Uganda I sub-lineage

IntroductionTuberculosis (TB) is the leading cause of morbidity and mortality globally, responsible for an estimated annual 10.0 million new cases and 1.3 million deaths among infectious diseases with Africa contributing a quarter of these cases in 2019. Classification of Mycobacterium tuberculosis (MTB) strains is important in understanding their geographical predominance and pathogenicity. Different studies have gone ahead to classify MTB using different methods. Some of these include; RFLP, spoligotyping, MIRU-VNTR and SNP set based phylogeny. The SNP set based classification has been found to be in concordance with the region of difference (RD) analysis of MTB complex classification system. In Uganda, the most common cause of pulmonary tuberculosis (PTB) is Uganda genotype of MTB and accounts for up to 70 % of isolates. MethodsSequenced MTB genome samples were retrieved from NCBI and others from local sequencing projects. The genomes were subjected to snippy (a rapid haploid variant calling and core genome alignment) to call variants and annotate them. Outputs from snippy were used to classify the isolates into Uganda genotypes and Non Ugandan genotypes based on 62 SNP set. The Ugandan genotype isolates were later subjected to 413 SNP set and then to a pan genome wide association analysis. Results6 Uganda genotype isolates were found not to classify as either Uganda I or II genotypes based on the 62 SNP set. Using the 413 SNP set, the 6 Uganda genotype isolates were found to have only one SNP out of the 7 SNPs that classify the Uganda I genotypes. They were also found to have both missense and frameshift mutations within the ctpH gene whereas the rest of Uganda I that had a mutation within this gene, was a missense. ConclusionAmong the Uganda genotypes genomes, Uganda I genomes are unstable. We used publicly available datasets to perform analysis like mapping, variant calling, mixed infection, pan-genome analysis to investigate and compare evolution of the Ugandan genotype.

bioinformatics↗

bioRxiv2020

Genome ARTIST_v2 software - a support for annotation of class II natural transposons in new sequenced genomes

Transposon annotation is a very dynamic field of genomics and various tools assigned to support this bioinformatics endeavor were reported. Genome ARTIST (GA) software was initially developed for mapping artificial transposons mobilized during insertional mutagenesis projects. Now, the new functions of GA_v2 qualify it as an effective companion for mapping and annotation of class II natural transposons in assembled genomes, contigs or sequencing reads. Tabular export of mapping and annotation data for subsequent high-throughput data analysis, the export of a list of flanking sequences around either the coordinates of insertion or around the target site duplications (TSDs) and generation of a consensus sequence for the respective flanking sequences are all key assets of GA_v2. Additionally, we developed two accompanying short scripts that enable the user to annotate transposons existent in assembled genomes and to use various annotation offered by FlyBase for Drosophila melanogaster genome. Herein, we present the applicability of GA_v2 for a preliminary annotation of the class II transposon P-element in the genome of D. melanogaster strain Horezu, Romania, which was sequenced with Nanopore technology in our laboratory. Our results point that GA_v2 is a reliable tool to be integrated in pipelines designed to perform transposon annotation in new sequenced genomes. GA_v2 is open source software compatible with Ubuntu, Mac OS and Windows and is available at https://github.com/genomeartist/genomeartist and at www.genomeartist.ro.

bioinformatics↗

bioRxiv2021

The genome of a daddy-long-legs (Opiliones) illuminates the evolution of arachnid appendages and chelicerate genome architecture

Chelicerates exhibit dynamic evolution of genome architecture, with multiple whole genome duplication events affecting groups like spiders, scorpions, and horseshoe crabs. Yet, genomes remain unavailable for several chelicerate orders, such as Opiliones (harvestmen), which has hindered comparative genomics and developmental genetics across arachnids. We assembled a draft genome of the daddy-long-legs Phalangium opilio, which revealed no signal of whole genome duplication. To test the hypothesis that single-copy Hox genes of the harvestman exhibit broader functions than subfunctionalized spider paralogs, we performed RNA interference against Deformed in P. opilio. Knockdown of Deformed incurred homeotic transformation of the two anterior pairs of walking legs into pedipalpal identity; by comparison, knockdown of the spatially restricted paralog Deformed-A in the spider affects only the first walking leg. To investigate the genetic basis for leg elongation and tarsomere patterning, we identified and interrogated the function of an Epidermal growth factor receptor (Egfr) homolog. Knockdown of Egfr incurred shortened appendages and the loss of distal leg structures. The overlapping phenotypic spectra of Egfr knockdown experiments in the harvestman and multiple insect models are striking because tarsomeres have evolved independently in these groups. Our results suggest a conserved role for Egfr in patterning distal leg structures across arthropods, as well as cooption of EGFR signaling in tarsomere patterning in both insects and arachnids. The establishment of genomic resources for P. opilio, together with functional investigations of appendage fate specification and distal patterning mechanisms, are key steps in understanding how daddy-long-legs make their long legs.

developmental biology↗