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. 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.
E. Nishiduka, Tom Hill, Stephen Lu et al.· bioRxiv· 0 citations
Complement inhibition is a key strategy used by many blood-feeding arthropods to ensure successful feeding. Mosquitoes, ticks, sand flies, and other hematophagous species secrete salivary proteins that block different steps of the complement cascade. These inhibitors prevent complement-mediated lysis and inflammation at the feeding site, allowing the arthropod to feed efficiently while also creating a more permissive environment for pathogen transmission
Here, we characterize the anti-complement activity of Sicpin, a salivary protein from the blackfly Simulium nigrimanum. Sicpin was found to inhibit all three pathways of complement activation. Surface plasmon resonance analysis revealed a strong and specific interaction with C3, with no detectable binding to other complement components common to the pathways.
The binding induces a conformational change in C3 that blocks the interaction with the C3 convertase, consequently inhibiting the deposition of downstream complement proteins. Additionally, in both acute lung injury and sepsis models, Sicpin enhances survival and exhibits anti-inflammatory activity.
These findings support that Sicpin modulates the complement system, with potential implications for pathogen transmission, blood feeding, and therapeutic development
NIH
Innate Immune Responses and Host Defense: Molecular Mechanisms (INM)
Paola Carolina Valenzuela Leon, Molly Ring, Brian Bonilla et al.· Journal of Immunology· 0 citations
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