Genome divergence and reproductive incompatibility among populations of Ganaspis near brasiliensis.

During the last decade, the spotted wing drosophila, Drosophila suzukii, has spread from eastern Asia to the Americas, Europe, and Africa. This fly attacks many species of cultivated and wild fruits with soft, thin skins, where its serrated ovipositor allows it to lay eggs in undamaged fruit. Parasitoids from the native range of D. suzukii may provide sustainable management of this polyphagous pest. Among these parasitoids, host-specificity testing has revealed a lineage of Ganaspis near brasiliensis, referred to in this paper as G1, that appears to be a cryptic species more host-specific to D. suzukii than other parasitoids. Differentiation among cryptic species is critical for introduction and subsequent evaluation of their impact on D. suzukii. Here, we present results on divergence in genomic sequences and architecture and reproductive isolation between lineages of Ganaspis near brasiliensis that appear to be cryptic species. We studied five populations, two from China, two from Japan, and one from Canada, identified as the G1 vs G3 lineages based on differences in cytochrome oxidase l sequences. We assembled and annotated the genomes of these populations and analyzed divergences in sequence and genome architecture between them. We also report results from crosses to test reproductive compatibility between the G3 lineage from China and the G1 lineage from Japan. The combined results on sequence divergence, differences in genome architectures, ortholog divergence, reproductive incompatibility, differences in host ranges and microhabitat preferences, and differences in morphology show that these lineages are different species. Thus, the decision to evaluate the lineages separately and only import and introduce the more host-specific lineage to North America and Europe was appropriate.

A multitiered haplotype strategy to enhance phased assembly and fine mapping of a disease resistance locus.

Fine mapping of quantitative trait loci (QTL) to dissect the genetic basis of traits of interest is essential to modern breeding practice. Here, we employed a multitiered haplotypic marker system to increase fine mapping accuracy by constructing a chromosome-level, haplotype-resolved parental genome, accurate detection of recombination sites, and allele-specific characterization of the transcriptome. In the first tier of this system, we applied the preexisting panel of 2,000 rhAmpSeq core genome markers that is transferable across the entire Vitis genus and provides a genomic resolution of 200 kb to 1 Mb. The second tier consisted of high-density haplotypic markers generated from Illumina skim sequencing data for samples enriched for relevant recombinations, increasing the potential resolution to hundreds of base pairs. We used this approach to dissect a novel Resistance to Plasmopara viticola-33 (RPV33) locus conferring resistance to grapevine downy mildew, narrowing the candidate region to only 0.46 Mb. In the third tier, we used allele-specific RNA-seq analysis to identify a cluster of 3 putative disease resistance RPP13-like protein 2 genes located tandemly in a nonsyntenic insertion as candidates for the disease resistance trait. In addition, combining the rhAmpSeq core genome haplotype markers and skim sequencing-derived high-density haplotype markers enabled chromosomal-level scaffolding and phasing of the grape Vitis × doaniana 'PI 588149' assembly, initially built solely from Pacific Biosciences (PacBio) high-fidelity (HiFi) reads, leading to the correction of 16 large-scale phasing errors. Our mapping strategy integrates high-density, phased genetic information with individual reference genomes to pinpoint the genetic basis of QTLs and will likely be widely adopted in highly heterozygous species.

Long-read isoform sequencing reveals tissue-specific isoform expression between active and hibernating brown bears (Ursus arctos).

Understanding hibernation in brown bears (Ursus arctos) can provide insight into some human diseases. During hibernation, brown bears experience periods of insulin resistance, physical inactivity, extreme bradycardia, obesity, and the absence of urine production. These states closely mimic aspects of human diseases such as type 2 diabetes, muscle atrophy, as well as renal and heart failure. The reversibility of these states from hibernation to active season enables the identification of mediators with possible therapeutic value for humans. Recent studies have identified genes and pathways that are differentially expressed between active and hibernation seasons in bears. However, little is known about the role of differential expression of gene isoforms on hibernation physiology. To identify both distinct and novel mRNA isoforms, full-length RNA-sequencing (Iso-Seq) was performed on adipose, skeletal muscle, and liver from three individual bears sampled during both active and hibernation seasons. The existing reference genome annotation was improved by combining it with the Iso-Seq data. Short-read RNA-sequencing data from six individuals were mapped to the new reference annotation to quantify differential isoform usage (DIU) between tissues and seasons. We identified differentially expressed isoforms in all three tissues, to varying degrees. Adipose had a high level of DIU with isoform switching, regardless of whether the genes were differentially expressed. Our analyses revealed that DIU, even in the absence of differential gene expression, is an important mechanism for modulating genes during hibernation. These findings demonstrate the value of isoform expression studies and will serve as the basis for deeper exploration into hibernation biology.

Rapid Development and Validation of a Novel Laboratory-Derived Test for the Detection of SARS-CoV-2.

OBJECTIVES: To increase testing capability for SARS-CoV-2 during a rapidly evolving public health emergency, we aimed to deploy a validated laboratory-developed real-time reverse transcription polymerase chain reaction (RT-PCR) diagnostic test for SARS-CoV-2 on an accelerated timeline and using reagent supply chains that were not constrained. METHODS: A real-time RT-PCR assay that detects the structural envelope (E) gene of SARS-CoV-2 was developed and validated on the Roche cobas 6800 instrument platform with the omni Utility channel reagents, which performs automated nucleic acid extraction and purification, PCR amplification, and detection. In silico analysis was performed for both inclusivity of all SARS-CoV-2 variants and cross reactivity with other pathogenic organisms. Positive control material was used to determine the Limit of Detection (LOD) and patient samples (positive and negative) confirmed by another authorized assay were used for clinical validation. Experiments were carried out at the Christiana Care Health System's Molecular Diagnostics Laboratory (Newark, DE) between April 1 and April 4, 2020. RESULTS: A real-time RT-PCR assay for SARS-Cov-2 was developed and validated in just two weeks. For all oligonucleotides, 100% homology to the available SARS-CoV-2 sequences was observed. Greater than 80% homology between one or more oligonucleotides was observed for SARS-Cov (Urbani strain) and Influenza A, however risk of cross reactivity was deemed to be low. The limit of detection (LOD) of the assay was 250 copies/mL. The assay identified 100% of positive patient samples (30/30) and 100% of negative patient samples (29/29 patient negatives and 1/1 saline). Up to 92 samples can be run on a single plate and analysis takes approximately 3.5 hours. CONCLUSIONS: In this work, we demonstrate the development and validation of a single target laboratory-developed test for SARS-CoV-2 in two weeks. Key considerations for complementary supply chains enabled development on an accelerated timeline and an increase in testing capability.

Genome sequencing and transcript analysis of Hemileia vastatrix reveal expression dynamics of candidate effectors dependent on host compatibility.

Coffee leaf rust caused by the fungus Hemileia vastatrix is one of the most important leaf diseases of coffee plantations worldwide. Current knowledge of the H. vastatrix genome is limited and only a small fraction of the total fungal secretome has been identified. In order to obtain a more comprehensive understanding of its secretome, we aimed to sequence and assemble the entire H. vastatrix genome using two next-generation sequencing platforms and a hybrid assembly strategy. This resulted in a 547 Mb genome of H. vastatrix race XXXIII (Hv33), with 13,364 predicted genes that encode 13,034 putative proteins with transcriptomic support. Based on this proteome, 615 proteins contain putative secretion peptides, and lack transmembrane domains. From this putative secretome, 111 proteins were identified as candidate effectors (EHv33) unique to H. vastatrix, and a subset consisting of 17 EHv33 genes was selected for a temporal gene expression analysis during infection. Five genes were significantly induced early during an incompatible interaction, indicating their potential role as pre-haustorial effectors possibly recognized by the resistant coffee genotype. Another nine genes were significantly induced after haustorium formation in the compatible interaction. Overall, we suggest that this fungus is able to selectively mount its survival strategy with effectors that depend on the host genotype involved in the infection process.

Complete Genome Sequence of Vibrio coralliilyticus RE22, a Marine Bacterium Pathogenic toward Larval Shellfish.

Vibrio coralliilyticus RE22 is an indigenous marine pathogen that infects larval bivalve shellfish. This strain is particularly problematic in oyster hatcheries, where it causes high larval mortality. It contains two circular chromosomes and one megaplasmid. Annotation reveals multiple genes which may encode important virulence factors.

A reference genome of the Chinese hamster based on a hybrid assembly strategy.

Accurate and complete genome sequences are essential in biotechnology to facilitate genome-based cell engineering efforts. The current genome assemblies for Cricetulus griseus, the Chinese hamster, are fragmented and replete with gap sequences and misassemblies, consistent with most short-read-based assemblies. Here, we completely resequenced C. griseus using single molecule real time sequencing and merged this with Illumina-based assemblies. This generated a more contiguous and complete genome assembly than either technology alone, reducing the number of scaffolds by >28-fold, with 90% of the sequence in the 122 longest scaffolds. Most genes are now found in single scaffolds, including up- and downstream regulatory elements, enabling improved study of noncoding regions. With >95% of the gap sequence filled, important Chinese hamster ovary cell mutations have been detected in draft assembly gaps. This new assembly will be an invaluable resource for continued basic and pharmaceutical research.

Transcriptome profiling of spinal muscular atrophy motor neurons derived from mouse embryonic stem cells.

Proximal spinal muscular atrophy (SMA) is an early onset, autosomal recessive motor neuron disease caused by loss of or mutation in SMN1 (survival motor neuron 1). Despite understanding the genetic basis underlying this disease, it is still not known why motor neurons (MNs) are selectively affected by the loss of the ubiquitously expressed SMN protein. Using a mouse embryonic stem cell (mESC) model for severe SMA, the RNA transcript profiles (transcriptomes) between control and severe SMA (SMN2+/+;mSmn-/-) mESC-derived MNs were compared in this study using massively parallel RNA sequencing (RNA-Seq). The MN differentiation efficiencies between control and severe SMA mESCs were similar. RNA-Seq analysis identified 3,094 upregulated and 6,964 downregulated transcripts in SMA mESC-derived MNs when compared against control cells. Pathway and network analysis of the differentially expressed RNA transcripts showed that pluripotency and cell proliferation transcripts were significantly increased in SMA MNs while transcripts related to neuronal development and activity were reduced. The differential expression of selected transcripts such as Crabp1, Crabp2 and Nkx2.2 was validated in a second mESC model for SMA as well as in the spinal cords of low copy SMN2 severe SMA mice. Furthermore, the levels of these selected transcripts were restored in high copy SMN2 rescue mouse spinal cords when compared against low copy SMN2 severe SMA mice. These findings suggest that SMN deficiency affects processes critical for normal development and maintenance of MNs.

Identification of a HMGA2-EFCAB6 gene rearrangement following next-generation sequencing in a patient with a t(12;22)(q14.3;q13.2) and JAK2V617F-positive myeloproliferative neoplasm.

Myeloproliferative neoplasms (MPNs) result from genetically altered hematopoietic stem cells that retain the capacity for multilineage differentiation. The study of genomic mutations identified so far suggests that they occur after a common ancestral event or that different mutations result in similar MPN phenotypes. We report analysis of a chromosomal translocation, t(12;22)(q14.3;q13.2), in a patient with a BCR-ABL1-negative, JAK2V617F-positive MPN. Comparative genomic hybridization (CGH) array and targeted sequencing detected no mutation in nine genes reported to influence the JAK2V617F-driven MPNs (MPL, LNK, CBL, TET2, EZH2, IKZF1, IDH1, IDH2, ASXL1). Next-generation sequencing revealed a balanced HMGA2-EFCAB6 genomic rearrangement. The HMGA2 breakpoint leads to the loss of seven 3'UTR binding sites for the microRNA (miRNA) let-7 tumor suppressor. The breakpoint in the EFCAB6 gene abrogates transcription of EFCAB6. Measurement of expression showed retention of HMGA2 transcription and no detectable EFCAB6 transcript. Allele burden comparison in a sample containing the translocation, showed 90% HMGA2-EFCAB6 versus 50% JAK2V617F allele dose, suggesting HMGA2-EFCAB6 rearrangement plays a more ancestral role, pre-JAK2V617F, in the neoplastic process. The pathogenicity of the translocation may rest on collaborations among JAK2V617F-induced constitutive activation of JAK2, the oncogenic property of HMGA2, and disrupted pathways, such as alteration in DJ-1 expression, resulting from the impact of EFCAB6 abrogation.

Community annotation and bioinformatics workforce development in concert--Little Skate Genome Annotation Workshops and Jamborees.

Recent advances in high-throughput DNA sequencing technologies have equipped biologists with a powerful new set of tools for advancing research goals. The resulting flood of sequence data has made it critically important to train the next generation of scientists to handle the inherent bioinformatic challenges. The North East Bioinformatics Collaborative (NEBC) is undertaking the genome sequencing and annotation of the little skate (Leucoraja erinacea) to promote advancement of bioinformatics infrastructure in our region, with an emphasis on practical education to create a critical mass of informatically savvy life scientists. In support of the Little Skate Genome Project, the NEBC members have developed several annotation workshops and jamborees to provide training in genome sequencing, annotation and analysis. Acting as a nexus for both curation activities and dissemination of project data, a project web portal, SkateBase (http://skatebase.org) has been developed. As a case study to illustrate effective coupling of community annotation with workforce development, we report the results of the Mitochondrial Genome Annotation Jamborees organized to annotate the first completely assembled element of the Little Skate Genome Project, as a culminating experience for participants from our three prior annotation workshops. We are applying the physical/virtual infrastructure and lessons learned from these activities to enhance and streamline the genome annotation workflow, as we look toward our continuing efforts for larger-scale functional and structural community annotation of the L. erinacea genome.

BRCA1 E1644X: a deleterious mutation in an African American individual with early onset breast cancer.

An African American individual with early onset breast cancer has a unique BRCA1 germline mutation, E1644X, that truncates the protein's carboxy terminal region. DNA sequencing for E1644X mutation and five BRCA1 exon-11 single nucleotide polymorphisms showed tumor LOH. Clinical history suggests paternal transmission of the deleterious allele, and tumor polymorphisms provide some insight into the ancestral origins of the mutation.

The genome of herpesvirus of turkeys: comparative analysis with Marek's disease viruses.

The complete coding sequence of the herpesvirus of turkeys (HVT) unique long (U(L)) region along with the internal repeat regions has been determined. This allows completion of the HVT nucleotide sequence by linkage to the sequence of the unique short (U(S)) region. The genome is approximately 160 kbp and shows extensive similarity in organization to the genomes of Marek's disease virus serotypes 1 and 2 (MDV-1, MDV-2) and other alphaherpesviruses. The HVT genome contains 75 ORFs, with three ORFs present in two copies. Sixty-seven ORFs were identified readily as homologues of other alphaherpesvirus genes. Seven of the remaining eight ORFs are homologous to genes in MDV, but are absent from other herpesviruses. These include a gene with similarity to cellular lipases. The final, HVT-unique gene is a virus homologue of the cellular NR-13 gene, the product of which belongs to the Bcl family of proteins that regulate apoptosis. No other herpesvirus sequenced to date contains a homologue of this gene. Of potential significance is the absence of a complete block of genes within the HVT internal repeat that is present in MDV-1. These include the pp38 and meq genes, which have been implicated in MDV-1-induced T-cell lymphoma. By implication, other genes present in this region of MDV-1, but missing in HVT, may play important roles in the different biological properties of the viruses.