Browsing by Author "Son, Jae Hak"

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    Genome-wide association of trypanosome infection status in the tsetse fly Glossina fuscipes, the major vector of African trypanosomiasis in Uganda
    (Research Square, 2022) Saarman, Norah; Son, Jae Hak; Zhao, Hongyu; Cosme, Luciano; Kong, Yong; Li, Mo; Wang, Shiyu; Weiss, Brian; Echodu, Richard; Opiro, Robert; Aksoy, Serap; Caccone, Adalgisa
    The primary vector of the trypanosome parasite causing human and animal African trypanosomiasis in Uganda is the riverine tsetse fly Glossina fuscipes fuscipes (Gff). We conducted a genome-wide association (GWA) analysis with field-caught Gff. To increase statistical power, we first improved the Gff genome assembly with whole genome 10X Chromium sequencing, used ddRAD-seq to identify autosomal versus sex-chromosomal regions of the genome with data from 96,965 SNPs, and conducted a GWA with a subset of 50,960 autosomal SNPs from 351 flies. Results assigned a full third of the genome to the sex chromosome, suggested possible sex-chromosome aneuploidy in Gff, and identified a single autosomal SNP to be highly associated with trypanosome infection. The top SNP was ~ 1200 bp upstream of the gene lecithin cholesterol acyltransferase (LCAT), an important component of the molecular pathway that initiates trypanosome lysis and protection in mammals. Results indicate that variation upstream of LCAT and/or linked genetic elements are associated with trypanosome infection susceptibility in Gff. This suggests that there may be naturally occurring genetic variation in Gff that can protect against trypanosome infection, thereby paving the way for targeted research into novel vector control strategies that can promote parasite resistance in natural populations.
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    Infection with endosymbiotic Spiroplasma disrupts tsetse (Glossina fuscipes fuscipes) metabolic and reproductive homeostasis
    (PLoS pathogens, 2021) Son, Jae Hak; Weiss, Brian L.; Schneider, Daniela I.; Dera, Kiswend-sida M.; Gstottenmayer, Fabian; Opiro, Robert; Echodu, Richard; Saarman, Norah P.; Attardo, Geoffrey M.; Onyango, Maria; Abd-Alla, Adly M. M.; Aksoy, Serap
    Tsetse flies (Glossina spp.) house a population-dependent assortment of microorganisms that can include pathogenic African trypanosomes and maternally transmitted endosymbiotic bacteria, the latter of which mediate numerous aspects of their host’s metabolic, reproductive, and immune physiologies. One of these endosymbionts, Spiroplasma, was recently discovered to reside within multiple tissues of field captured and laboratory colonized tsetse flies grouped in the Palpalis subgenera. In various arthropods, Spiroplasma induces reproductive abnormalities and pathogen protective phenotypes. In tsetse, Spiroplasma infections also induce a protective phenotype by enhancing the fly’s resistance to infection with trypanosomes. However, the potential impact of Spiroplasma on tsetse’s viviparous reproductive physiology remains unknown. Herein we employed high-throughput RNA sequencing and laboratory-based functional assays to better characterize the association between Spiroplasma and the metabolic and reproductive physiologies of G. fuscipes fuscipes (Gff), a prominent vector of human disease. Using field-captured Gff, we discovered that Spiroplasma infection induces changes of sex-biased gene expression in reproductive tissues that may be critical for tsetse’s reproductive fitness. Using a Gff lab line composed of individuals heterogeneously infected with Spiroplasma, we observed that the bacterium and tsetse host compete for finite nutrients, which negatively impact female fecundity by increasing the length of intrauterine larval development. Additionally, we found that when males are infected with Spiroplasma, the motility of their sperm is compromised following transfer to the female spermatheca. As such, Spiroplasma infections appear to adversely impact male reproductive fitness by decreasing the competitiveness of their sperm. Finally, we determined that the bacterium is maternally transmitted to intrauterine larva at a high frequency, while paternal transmission was also noted in a small number of matings. Taken together, our findings indicate that Spiroplasma exerts a negative impact on tsetse fecundity, an outcome that could be exploited for reducing tsetse population size and thus disease transmission.