Biology subjects

Masonbrink, R. E.

Publications and source records attributed to Masonbrink, R. E..

7 recordsLinked to original sources

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↗

bioRxiv2026

Recurrent Duplication of the REST-NOA1 Locus Reveals a Hotspot of Regulatory Evolution Across Even-Toed Ungulates

Gene duplication is a major source of evolutionary novelty, yet recurrent duplication of the same genomic locus across independent lineages remains understudied. Using a chromosome-scale assembly and de novo annotation of the North American bison (Bison bison), we investigated the mechanisms underlying immune-system diversification in ungulates. Comparative genomics of bison, cattle, elk, and 13 mammalian species identified a large segmental duplication encompassing the regulatory genes REST and NOA1. Although similar duplications were present in 14/16 species examined, phylogenetic analyses revealed that duplicated genes cluster within species rather than across taxa, indicating repeated independent origins rather inheritance from a common ancestor. To characterize the evolutionary consequences of this duplication, we integrated transcriptomics from six tissues with weighted gene co-expression and comparative protein clustering. We identified extensive structural divergence among duplicated copies of REST and NOA1, including domain losses, truncations, and expression partitioning across tissues, consistent with functional divergence following duplication. Comparative analyses revealed substantial remodeling of immune-related genes in bison, including BOLA class I molecules, T-cell receptor genes, leukocyte immunoglobulin-like receptors, and regulators of immune signaling. These modifications included domain rearrangements, novel sequence insertions, and lineage-specific duplications associated with immune-related expression networks. Together, these findings identify the REST-NOA1 locus as a recurrent hotspot of segmental duplication in ungulates and demonstrate how repeated duplication, structural divergence, and regulatory partitioning contribute to genome evolution. These results suggest that immune system diversification in bison and related species has been shaped not only by sequence evolution but also by recurrent remodeling of regulatory pathways and antigen-recognition pathways.

bioinformatics↗

bioRxiv2024

The Soybean Cyst Nematode Effector Cysteine Protease 1 (CPR1) Targets a Mitochondrial Soybean Branched-Chain Amino Acid Aminotransferase (GmBCAT1) for Degradation

The soybean cyst nematode (SCN; Heterodera glycines) facilitates infection by secreting a repertoire of effector proteins into host cells to establish a permanent feeding site composed of a syncytium of root cells. Among the diverse proteins secreted by the nematode, we were specifically interested in identifying proteases to pursue our goal of engineering decoy substrates that elicit an immune response when cleaved by an SCN protease. We identified a cysteine protease that we named Cysteine Protease 1 (CPR1), which was predicted to be a secreted effector based on transcriptomic data obtained from SCN esophageal gland cells, presence of a signal peptide, and lack of transmembrane domains. CPR1 is conserved in all isolates of SCN sequenced to date, suggesting it is critical for virulence. Transient expression of CPR1 in Nicotiana benthamiana leaves suppressed cell death induced by a constitutively active nucleotide binding leucine-rich repeat protein, RPS5, indicating that CPR1 inhibits effector-triggered immunity. CPR1 localizes in part to the mitochondria when expressed in planta. Proximity-based labeling in transgenic soybean roots, co-immunoprecipitation, and cleavage assays identified a branched-chain amino acid aminotransferase from soybean (GmBCAT1) as a substrate of CPR1. Silencing of the CPR1 transcript in the nematode reduced penetration frequency in soybean roots while the expression of CPR1 in soybean roots enhanced susceptibility. Our data demonstrates that CPR1 is a conserved effector protease with a direct target in soybean roots, highlighting it as a promising candidate for decoy engineering.

plant biology↗

bioRxiv2024

Chromosome-level genome assembly of the disco clam, Ctenoides ales, a first for the bivalve order Limida

The bivalve subclass Pteriomorphia, which includes the economically important scallops, oysters, mussels, and ark clams, exhibits extreme ecological, morphological, and behavioral diversity. Among this diversity are five morphologically distinct eye types, making Pteriomorphia an excellent setting to explore the molecular basis for the evolution of novel traits. Of pteriomorphian bivalves, Limida is the only order lacking genomic resources, greatly limiting the potential phylogenomic analyses related to eyes and phototransduction. Here, we present the first limid genome assembly, the disco clam, Ctenoides ales, which is characterized by invaginated eyes, exceptionally long tentacles, and a flashing light display. This genome assembly was constructed with PacBio long reads and Dovetail Omni-CTM proximity-ligation sequencing. The final assembly is [~]2.3Gb and over 99% of the total length is contained in 18 pseudomolecule scaffolds. We annotated 41,064 protein coding genes and report a BUSCO completeness of 91.9% for metazoa_obd10. Additionally, we report a completely annotated mitochondrial genome, also a first for Limida. The [~]20Kb mitogenome has 12 protein coding genes, 22 tRNAs, 2 rRNA genes, and a 1,589 bp duplicated sequence containing the origin of replication. The C. ales nuclear genome size is substantially larger than other pteriomorphian genomes, mainly accounted for by transposable element sequences. We inventoried the genome for opsins, the signaling proteins that initiate phototransduction, and found that, unlike its closest eyed-relatives, the scallops, C. ales lacks duplication of the rhabdomeric Gq-protein coupled opsin that is typically used for invertebrate vision. In fact, C. ales has uncharacteristically few opsins relative to the other pteriomorphian families, all of which have unique expansions of xenopsins, a recently discovered opsin subfamily. This chromosome-level assembly, along with the mitogenome, will be valuable resources for comparative genomics and phylogenetics in bivalves and particularly for the understudied but charismatic limids. SignificanceThis high-quality chromosome-level genome assembly for Ctenoides ales, the disco clam, is the first genome sequenced from the bivalve order Limida, the only group of Pteriomorphia - a highly diverse and ecologically important clade - lacking genomic resources. The sequence and annotation of the C. ales genome will be a useful resource for molluscan phylogenetics and comparative genomics.

evolutionary biology↗

bioRxiv2024

The SUbventral-Gland master Regulator (SUGR) of nematode virulence

All pathogens must tailor their gene expression to their environment. Therefore, targeting host:parasite biology that regulates these changes in gene expression could open up routes to pathogen control. Here, we show that in the plant-parasitic nematode Heterodera schachtii, host signals (termed effectostimulins) within plant roots activate the master regulator sugr1. SUGR1, then, directly binds effector promoters, and orchestrates their production. Effector production, in turn, facilitates host entry, releasing more effectostimulins. These data show that gene expression during the very earliest stages of parasitism is defined by a feed forward loop for host entry. Importantly, we demonstrate that blocking SUGR1 blocks parasitism, underlining the SUGR1 signalling cascade as a valuable target for crop protection. Given that nematodes also parasitise humans and other animals, the potential impact is broad: disrupting effector production could, in principle, be applied to any pathogen that secrets effectors. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=146 SRC="FIGDIR/small/576598v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@cebedaorg.highwire.dtl.DTLVardef@153fe87org.highwire.dtl.DTLVardef@16b6957org.highwire.dtl.DTLVardef@d0e920_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2021

The genome and lifestage-specific transcriptomes of a plant-parasitic nematode and its host reveal susceptibility genes involved in trans-kingdom synthesis of vitamin B.

Plant-parasitic nematodes are a major, and in some cases a dominant, threat to crop production in all agricultural systems. The relative scarcity of classical resistance genes highlights a pressing need to identify new ways to develop nematode-resistant germplasm. Here, we sequence and assemble a high-quality genome of the model cyst nematode Heterodera schachtii to provide a platform for the first system-wide dual analysis of host and parasite gene expression over time, covering all major stages of the interaction. This novel approach enabled the analysis of the hologenome of the infection site, to identify metabolic pathways that were incomplete in the parasite but complemented by the host. Using a combination of bioinformatic, genetic, and biochemical approaches, we show that the highly atypical completion of vitamin B5 biosynthesis by the parasitic animal, putatively enabled by a horizontal gene transfer from a bacterium, is critically important for parasitism. Knockout of either the plant-encoded or the now nematode-encoded steps in the pathway blocks parasitism. Our experiments establish a reference for cyst nematodes, use this platform to further our fundamental understanding of the evolution of plant-parasitism by nematodes, and show that understanding congruent differential expression of metabolic pathways represents a new way to find nematode susceptibility genes, and thereby, targets for future genome editing-mediated generation of nematode-resistant crops.

genetics↗

bioRxiv2018

The genome of the soybean cyst nematode (Heterodera glycines) reveals complex patterns of duplications involved in the evolution of parasitism genes

Heterodera glycines, commonly referred to as the soybean cyst nematode (SCN), is an obligatory and sedentary plant parasite that causes over a billion-dollar yield loss to soybean production annually. Although there are genetic determinants that render soybean plants resistant to certain nematode genotypes, resistant soybean cultivars are increasingly ineffective because their multi-year usage has selected for virulent H. glycines populations. The parasitic success of H. glycines relies on the comprehensive re-engineering of an infection site into a syncytium, as well as the long-term suppression of host defense to ensure syncytial viability. At the forefront of these complex molecular interactions are effectors, the proteins secreted by H. glycines into host root tissues. The mechanisms of effector acquisition, diversification, and selection need to be understood before effective control strategies can be developed, but the lack of an annotated genome has been a major roadblock. Here, we use PacBio long-read technology to assemble a H. glycines genome of 738 contigs into 123Mb with annotations for 29,769 genes. The genome contains significant numbers of repeats (34%), tandem duplicates (18.7Mb), and horizontal gene transfer events (151 genes). Using previously published effector sequences, the newly generated H. glycines genome, and comparisons to other nematode genomes, we investigate the evolutionary mechanisms responsible for the emergence and diversification of effector genes.

genomics↗