Biology subjects

Solares, E. A.

Publications and source records attributed to Solares, E. A..

6 recordsLinked to original sources

bioRxiv2026

HapSolo2: GPU-accelerated optimization for removing secondary haplotigs from diploid genome assemblies

BackgroundSecondary haplotigs retained in a primary assembly inflate genome size and duplicate gene content, and their removal remains a necessary curation step for heterozygous diploid genomes. HapSolo (Solares et al. 2021) treats this step as an optimization problem: it searches three pairwise alignment thresholds (percent identity, query coverage, and the ratio of aligned query to aligned reference length) to minimize a cost defined over single-copy, duplicated, and missing conserved orthologs. The original implementation depended on a separate BUSCO v3 run for every contig, on Python 2.7 and pandas in its inner loop, on a single randomized forward-walk optimizer, and on OrthoDB v9 lineage datasets that are no longer distributed. ResultsHere we report HapSolo2, a reimplementation that replaces the per-contig BUSCO step with miniprot-based ortholog classification against OrthoDB v9, v10, or v12.2 lineage datasets, adds steepest descent and simulated annealing to the original random forward walk, and evaluates all walkers in batched CuPy array operations on a single GPU. On an avocado assembly of 5,122 contigs scored against 1,440 orthologs, 100,000 iterations of random walk and steepest descent ran 5.6- and 7.6-fold faster on one NVIDIA RTX A6000 than on 10 CPU processes. Across 45 runs on four diploid assemblies (Anopheles funestus, Persea americana, Vitis vinifera, and Amblyraja radi-ata; 212 Mb to 3.2 Gb) and three OrthoDB releases, the three optimizers reached best costs within 1.8% of one another. Independent assessment with BUSCO v6.1 showed that HapSolo2 reduced duplicated orthologs from 52.0% to 5.6% in P. americana, from 17.9% to 10.4% in V. vinifera, and from 7.8% to 2.8% in A. funestus, with completeness decreasing by at most 1.3 percentage points. On the avocado assembly, HapSolo2 reduced the cost reached by the original HapSolo from 0.2200 to 0.1036 and raised contig N50 from 3,366 kb to 4,608 kb. ConclusionsHapSolo2 makes ortholog-guided haplotig removal practical in minutes on a single workstation, independent of a BUSCO installation, and reproducible across OrthoDB releases. It is distributed as an installable Python package with a unified command-line pipeline, an assembly statistics and plotting tool, an Apptainer container, and archived copies of the legacy ortholog datasets.

bioinformatics↗

bioRxiv2022

Sex-linked gene traffic underlies the acquisition of sexually dimorphic UV color vision in Heliconius butterflies

Butterflies have photoreceptor cells that are sensitive to the ultraviolet part of the spectrum due to ultraviolet-sensitive rhodopsin (UVRh), a gene that has been duplicated in the Heliconius genus. In individuals expressing UVRh1 and UVRh2, electrophysiological and behavioral studies demonstrate that these opsin proteins enable discrimination of UV wavelengths. This behavioral trait varies between species, being absent in H. melpomene and limited to females in H. erato. To identify the evolutionary origins of this trait, we first examined UV color vision in H. charithonia, a species related to H. erato in the sara/sapho group. We found that this species also has sexually dimorphic UV color vision. To identify the genetic basis of this trait, we built a reference-grade genome assembly of H. charithonia. We discovered that one duplicate, UVRh1, is present on the W chromosome, making it obligately female-specific. We employed gDNA PCR assays of UVRh1 across the Heliconius genus. In species with sexually dimorphic UVRh1 mRNA expression, UVRh1 gDNA is absent in males, whereas in species with sexually monomorphic UVRh1 mRNA expression, UVRh1 gDNA is found in both sexes. The presence or absence of male UVRh1 expression across the Heliconius phylogeny supports a model where sexual dimorphism was acquired early via movement of a gene duplication to the W-chromosome. We used CRISPR-Cas9 to engineer a deletion in the UVRh1 locus in female H. charithonia and use immunohistochemistry to show that UVRh1 protein expression is absent in mutant tissue, similar to that of males. Our results show that a rare behavioral phenotype, sex-specific UV color vision, was acquired via sex chromosome gene traffic of a duplicated UV rhodopsin.

evolutionary biology↗

bioRxiv2022

Insights into the domestication of avocado and potential genetic contributors to heterodichogamy

O_LIThe domestication history of avocado (Persea americana) remains unclear, in part due to a lack of suitable genomic tools. C_LIO_LIWe created a reference genome from the Gwen varietal, which is closely related to the economically dominant Hass varietal. We also compiled a database of 34 resequenced accessions that represented the three botanical races of P. americana. C_LIO_LIOur genome assembly had an N50 of 3.37 megabases, a BUSCO score of 91% and was scaffolded with a genetic map, producing 12 pseudo-chromosomes with 49,450 genes. We used the Gwen genome as a reference to investigate the population genomics of avocado. Our analyses were consistent with three separate domestication events; we estimated that the Mexican race diverged from the Lowland (formerly known as West Indian) and Guatemalan races >1 million years ago. We also identified putative targets of selective sweeps in domestication events; within the Guatemalan race, putative candidate genes were enriched for fruit development and ripening. We also investigated divergence between heterodichogamous flowering types. C_LIO_LIWith the help of a new reference genome, we inferred the domestication history of avocado and identified genes that may contribute to heterodichogamy, including genes with functions in pollination and floral development. C_LI

genomics↗

bioRxiv2020

HapSolo: An optimization approach for removing secondary haplotigs during diploid genome assembly and scaffolding.

BackgroundDespite marked recent improvements in long-read sequencing technology, the assembly of diploid genomes remains a difficult task. A major obstacle is distinguishing between alternative contigs that represent highly heterozygous regions. If primary and secondary contigs are not properly identified, the primary assembly will overrepresent both the size and complexity of the genome, which complicates downstream analysis such as scaffolding. ResultsHere we illustrate a new method, which we call HapSolo, that identifies secondary contigs and defines a primary assembly based on multiple pairwise contig alignment metrics. HapSolo evaluates candidate primary assemblies using BUSCO scores and then distinguishes among candidate assemblies using a cost function. The cost function can be defined by the user but by default considers the number of missing, duplicated and single BUSCO genes within the assembly. HapSolo performs hill climbing to minimize cost over thousands of candidate assemblies. We illustrate the performance of HapSolo on genome data from three species: the Chardonnay grape (Vitis vinifera), with a genome of 490Mb, a mosquito (Anopheles funestus; 200Mb) and the Thorny Skate (Amblyraja radiata; 2,650 Mb). ConclusionsHapSolo rapidly identified candidate assemblies that yield improvements in assembly metrics, including decreased genome size and improved N50 scores. Contig N50 scores improved by 35%, 9% and 9% for Chardonnay, mosquito and the thorny skate, respectively, relative to unreduced primary assemblies. The benefits of HapSolo were amplified by down-stream analyses, which we illustrated by scaffolding with Hi-C data. We found, for example, that prior to the application of HapSolo, only 52% of the Chardonnay genome was captured in the largest 19 scaffolds, corresponding to the number of chromosomes. After the application of HapSolo, this value increased to ~84%. The improvements for mosquito scaffolding were similar to that of Chardonnay (from 61% to 86%), but even more pronounced for thorny skate. We compared the scaffolding results to assemblies that were based on another published method for identifying secondary contigs, with generally superior results for HapSolo.

bioinformatics↗

bioRxiv2018

Structural variants, clonal propagation, and genome evolution in grapevine (Vitis vinifera)

Little is known about the type and numbers of structural variants (SVs) in plant genomes, the evolutionary processes that shape SV variation, or their effects on phenotypes. Here we assembled the 605Mb genome of the Chardonnay grape (Vitis vinifera ssp. sativa), which we use to catalog SVs within and between genomes and also across 69 cultivars and wild accessions. SVs underlie widespread hemizygosity of protein coding genes within Chardonnay and genic presence-absence variation between cultivars. Negative selection acts against all SV types, but they also accrue as heterozygous, recessive mutations in clonally propagated grapevines. SV hotspots in the sex determination region and the berry color locus illustrate their impact on phenotype and the role of SVs as drivers of convergent phenotypic evolution.

evolutionary biology↗

bioRxiv2018

Rapid low-cost assembly of the Drosophila melanogaster reference genome using low-coverage, long-read sequencing

Accurate and comprehensive characterization of genetic variation is essential for deciphering the genetic basis of diseases and other phenotypes. A vast amount of genetic variation stems from large-scale sequence changes arising from the duplication, deletion, inversion, and translocation of sequences. In the past 10 years, high-throughput short reads have greatly expanded our ability to assay sequence variation due to single nucleotide polymorphisms. However, a recent de novo assembly of a second Drosophila melanogaster reference genome has revealed that short read genotyping methods miss hundreds of structural variants, including those affecting phenotypes. While genomes assembled using high-coverage long reads can achieve high levels of contiguity and completeness, concerns about cost, errors, and low yield have limited widespread adoption of such sequencing approaches. Here we resequenced the reference strain of D. melanogaster (ISO1) on a single Oxford Nanopore MinION flow cell run for 24 hours. Using only reads longer than 1 kb or with at least 30x coverage, we assembled a highly contiguous de novo genome. The addition of inexpensive paired reads and subsequent scaffolding using an optical map technology achieved an assembly with completeness and contiguity comparable to the D. melanogaster reference assembly. Comparison of our assembly to the reference assembly of ISO1 uncovered a number of structural variants (SVs), including novel LTR transposable element insertions and duplications affecting genes with developmental, behavioral, and metabolic functions. Collectively, these SVs provide a snapshot of the dynamics of genome evolution. Furthermore, our assembly and comparison to the D. melanogaster reference genome demonstrates that high-quality de novo assembly of reference genomes and comprehensive variant discovery using such assemblies are now possible by a single lab for under $1,000 (USD).

genomics↗