Publications by authors named "Yoonseong Park"

84 Publications

20-hydroxyecdysone regulates expression of methioninesulfoxide reductases through transcription factor FOXO in the red flour beetle, Tribolium castaneum.

Insect Biochem Mol Biol 2021 Apr 3;131:103546. Epub 2021 Feb 3.

College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, 225009, China; Joint International Research Laboratory of Agriculture AndAgri-Product Safety of the Ministry of Education, Yangzhou University, Yangzhou, 225009, China. Electronic address:

The oxidation of methionine (Met) by reactive oxygen species (ROS) causes detrimental effects on the protein functions. Methionine sulfoxide reductase (Msr) is the secondary antioxidant enzyme involved in protein repair, and is divided into two distinct classes, MsrA and MsrB, although the mechanisms underlying the transcriptional regulation of Msrs remain largely unknown. In this study, the full-length cDNAs encoding MsrA and three alternatively spliced isoforms of MsrB were isolated from the red flour beetle, Tribolium castaneum. Exposure of female adults to oxidative, heat and cold stresses induced expressions of both MsrA and MsrB. RNAi-mediated knockdown of MsrA and MsrB resulted in increased sensitivity of T. castaneum to paraquat-induced oxidative stress. Treatment with 20-hydroxyecdysone (20E) increased expression levels of both MsrA and MsrB. Knockdown of transcription factor forkhead box O (FOXO) decreased both MsrA and MsrB mRNA levels and abolished the induction of MsrA and MsrB by paraquat. Luciferase reporter assays revealed that FOXO directly activates the promoters of both MsrA and MsrB. Moreover, paraquat treatment induced expression of two ecdysone biosynthesis genes, Shade and Phantom, 20E upregulated exoression of FOXO, promoted FOXO nuclear translocation,and knockdown of FOXO abolished induction of MsrA and MsrB expression by 20E, suggesting that regulation of MsrA and MsrB by 20E was mediated by FOXO. Overall, these results provide important insights into the transcriptional regulation of insect Msrs.
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http://dx.doi.org/10.1016/j.ibmb.2021.103546DOI Listing
April 2021

The bacterial community of the lone star tick (Amblyomma americanum).

Parasit Vectors 2021 Jan 14;14(1):49. Epub 2021 Jan 14.

Central European Institute of Technology, Center for Zoonoses, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic.

Background: The lone star tick (Amblyomma americanum), an important vector of a wide range of human and animal pathogens, is very common throughout the East and Midwest of the USA. Ticks are known to carry non-pathogenic bacteria that may play a role in their vector competence for pathogens. Several previous studies using the high throughput sequencing (HTS) technologies reported the commensal bacteria in a tick midgut as abundant and diverse. In contrast, in our preliminary survey of the field collected adult lone star ticks, we found the number of culturable/viable bacteria very low.

Methods: We aimed to analyze the bacterial community of A. americanum by a parallel culture-dependent and a culture-independent approach applied to individual ticks.

Results: We analyzed 94 adult females collected in eastern Kansas and found that 60.8% of ticks had no culturable bacteria and the remaining ticks carried only 67.7 ± 42.8 colony-forming units (CFUs)/tick representing 26 genera. HTS of the 16S rRNA gene resulted in a total of 32 operational taxonomic units (OTUs) with the dominant endosymbiotic genera Coxiella and Rickettsia (> 95%). Remaining OTUs with very low abundance were typical soil bacterial taxa indicating their environmental origin.

Conclusions: No correlation was found between the CFU abundance and the relative abundance from the culture-independent approach. This suggests that many culturable taxa detected by HTS but not by culture-dependent method were not viable or were not in their culturable state. Overall, our HTS results show that the midgut bacterial community of A. americanum is very poor without a core microbiome and the majority of bacteria are endosymbiotic.
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http://dx.doi.org/10.1186/s13071-020-04550-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7807426PMC
January 2021

Broad-complex transcription factor mediates opposing hormonal regulation of two phylogenetically distant arginine kinase genes in Tribolium castaneum.

Commun Biol 2020 Oct 30;3(1):631. Epub 2020 Oct 30.

College of Horticulture and Plant Protection, Yangzhou University, 225009, Yangzhou, China.

The phosphoarginine-arginine kinase shuttle system plays a critical role in maintaining insect cellular energy homeostasis. Insect molting and metamorphosis are coordinated by fluctuations of the ecdysteroid and juvenile hormone. However, the hormonal regulation of insect arginine kinases remain largely elusive. In this report, we comparatively characterized two arginine kinase genes, TcAK1 and TcAK2, in Tribolium castaneum. Functional analysis using RNAi showed that TcAK1 and TcAK2 play similar roles in adult fertility and stress response. TcAK1 was detected in cytoplasm including mitochondria, whereas TcAK2 was detected in cytoplasm excluding mitochondria. Interestingly, TcAK1 expression was negatively regulated by 20-hydroxyecdysone and positively by juvenile hormone, whereas TcAK2 was regulated by the opposite pattern. RNAi, dual-luciferase reporter assays and electrophoretic mobility shift assay further revealed that the opposite hormonal regulation of TcAK1 and TcAK2 was mediated by transcription factor Broad-Complex. Finally, relatively stable AK activities were observed during larval-pupal metamorphosis, which was generally consistent with the constant ATP levels. These results provide new insights into the mechanisms underlying the ATP homeostasis in insects by revealing opposite hormonal regulation of two phylogenetically distant arginine kinase genes.
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http://dx.doi.org/10.1038/s42003-020-01354-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603314PMC
October 2020

Genome-enabled insights into the biology of thrips as crop pests.

BMC Biol 2020 10 19;18(1):142. Epub 2020 Oct 19.

Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St. Lucia, QLD, 4072, Australia.

Background: The western flower thrips, Frankliniella occidentalis (Pergande), is a globally invasive pest and plant virus vector on a wide array of food, fiber, and ornamental crops. The underlying genetic mechanisms of the processes governing thrips pest and vector biology, feeding behaviors, ecology, and insecticide resistance are largely unknown. To address this gap, we present the F. occidentalis draft genome assembly and official gene set.

Results: We report on the first genome sequence for any member of the insect order Thysanoptera. Benchmarking Universal Single-Copy Ortholog (BUSCO) assessments of the genome assembly (size = 415.8 Mb, scaffold N50 = 948.9 kb) revealed a relatively complete and well-annotated assembly in comparison to other insect genomes. The genome is unusually GC-rich (50%) compared to other insect genomes to date. The official gene set (OGS v1.0) contains 16,859 genes, of which ~ 10% were manually verified and corrected by our consortium. We focused on manual annotation, phylogenetic, and expression evidence analyses for gene sets centered on primary themes in the life histories and activities of plant-colonizing insects. Highlights include the following: (1) divergent clades and large expansions in genes associated with environmental sensing (chemosensory receptors) and detoxification (CYP4, CYP6, and CCE enzymes) of substances encountered in agricultural environments; (2) a comprehensive set of salivary gland genes supported by enriched expression; (3) apparent absence of members of the IMD innate immune defense pathway; and (4) developmental- and sex-specific expression analyses of genes associated with progression from larvae to adulthood through neometaboly, a distinct form of maturation differing from either incomplete or complete metamorphosis in the Insecta.

Conclusions: Analysis of the F. occidentalis genome offers insights into the polyphagous behavior of this insect pest that finds, colonizes, and survives on a widely diverse array of plants. The genomic resources presented here enable a more complete analysis of insect evolution and biology, providing a missing taxon for contemporary insect genomics-based analyses. Our study also offers a genomic benchmark for molecular and evolutionary investigations of other Thysanoptera species.
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http://dx.doi.org/10.1186/s12915-020-00862-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7570057PMC
October 2020

Cholinergic axons regulate type I acini in salivary glands of Ixodes ricinus and Ixodes scapularis ticks.

Sci Rep 2020 09 29;10(1):16054. Epub 2020 Sep 29.

UMR BIPAR, INRAE, Ecole Nationale Vétérinaire d'Alfort, ANSES, Université Paris-Est, Maisons-Alfort, France.

Regulatory factors controlling tick salivary glands (SGs) are direct upstream neural signaling pathways arising from the tick's central nervous system. Here we investigated the cholinergic signaling pathway in the SG of two hard tick species. We reconstructed the organization of the cholinergic gene locus, and then used in situ hybridization to localize mRNA encoding choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) in specific neural cells in the Ixodes synganglion. Immunohistochemical staining revealed that cholinergic axonal projections exclusively reached type I acini in the SG of both Ixodes species. In type I acini, the rich network of cholinergic axons terminate within the basolateral infoldings of the lamellate cells. We also characterized two types (A and B) of muscarinic acetylcholine receptors (mAChRs), which were expressed in Ixodes SG. We pharmacologically assessed mAChR-A to monitor intracellular calcium mobilization upon receptor activation. In vivo injection of vesamicol-a VAChT blocker-at the cholinergic synapse, suppressed forced water uptake by desiccated ticks, while injection of atropine, an mAChR-A antagonist, did not show any effect on water volume uptake. This study has uncovered a novel neurotransmitter signaling pathway in Ixodes SG, and suggests its role in water uptake by type I acini in desiccated ticks.
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http://dx.doi.org/10.1038/s41598-020-73077-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7524744PMC
September 2020

Transcriptome of the Mosquito in Response to Human Complement Proteins.

Int J Mol Sci 2020 Sep 9;21(18). Epub 2020 Sep 9.

Department of Entomology, Kansas State University, Manhattan, KS 66506, USA.

is the primary mosquito vector of several human arboviruses, including the dengue virus (DENV). Vector control is the principal intervention to decrease the transmission of these viruses. The characterization of molecules involved in the mosquito physiological responses to blood-feeding may help identify novel targets useful in designing effective control strategies. In this study, we evaluated the in vivo effect of feeding adult female mosquitoes with human red blood cells reconstituted with either heat-inactivated (IB) or normal plasma (NB). The RNA-seq based transcript expression of IB and NB mosquitoes was compared against sugar-fed (SF) mosquitoes. In in vitro experiments, we treated Aag2 cells with a recombinant version of complement proteins (hC3 or hC5a) and compared transcript expression to untreated control cells after 24 h. The transcript expression analysis revealed that human complement proteins modulate approximately 2300 transcripts involved in multiple biological functions, including immunity. We also found 161 upregulated and 168 downregulated transcripts differentially expressed when human complement protein C3 (hC3) and human complement protein C5a (hC5a) treated cells were compared to the control untreated cells. We conclude that active human complement induces significant changes to the transcriptome of mosquitoes, which may influence the physiology of these arthropods.
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http://dx.doi.org/10.3390/ijms21186584DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7555780PMC
September 2020

Proteomics of the Honeydew from the Brown Planthopper and Green Rice Leafhopper Reveal They Are Rich in Proteins from Insects, Rice Plant and Bacteria.

Insects 2020 Sep 1;11(9). Epub 2020 Sep 1.

Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.

Honeydew is a watery fluid excreted by plant sap-feeding insects. It is a waste product for the insect hosts. However, it plays important roles for other organisms, such as serving as a nutritional source for beneficial insects and bacteria, as well as elicitors and effectors modulating plant responses. In this study, shotgun LC-MS/MS analyses were used to identify the proteins in the honeydew from two important rice hemipteran pests, the brown planthopper (, BPH) and green rice leafhopper (, GRH). A total of 277 and 210 proteins annotated to insect proteins were identified in the BPH and GRH honeydews, respectively. These included saliva proteins that may have similar functions as the saliva proteins, such as calcium-binding proteins and apolipophorin, involved in rice plant defenses. Additionally, a total of 52 and 32 proteins were identified in the BPH and GRH honeydews, respectively, some of which are involved in the plant immune system, such as Pathogen-Related Protein 10, ascorbate peroxidase, thioredoxin and glutaredoxin. Coincidently, 570 and 494 bacteria proteins were identified from the BPH and GRH honeydews, respectively, which included several well-known proteins involved in the plant immune system: elongation factor Tu, flagellin, GroEL and cold-shock proteins. The results of our study indicate that the insect honeydew is a complex fluid cocktail that contains abundant proteins from insects, plants and microbes, which may be involved in the multitrophic interactions of plants-insects-microbes.
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http://dx.doi.org/10.3390/insects11090582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564128PMC
September 2020

Differential localization of Hessian fly candidate effectors in resistant and susceptible wheat plants.

Plant Direct 2020 Aug 14;4(8):e00246. Epub 2020 Aug 14.

Department of Entomology Kansas State University Manhattan KS USA.

Hessian fly is a notorious pest of wheat. Previous studies suggest that Hessian fly uses effector-based mechanisms to attack wheat plants during parasitism, but no direct evidence has been reported to support this postulation. Here, we produced recombinant proteins for five Family-1 candidate effectors and antibodies. Indirect immunostaining and western blots were carried out to examine the localization of Hessian fly Family-1 proteins in plant and insect tissues. Confocal images revealed that Family-1 putative effectors were exclusively produced in the basal region of larval salivary glands, which are directly linked to the mandibles' ducts for effector injection. The five Family-1 proteins were detected in infested host plants on western blots. Indirect immunostaining of sectioned host tissues around the feeding site revealed strikingly different localization patterns between resistant and susceptible plants. In susceptible plants, the Family-1 proteins penetrated from the feeding cell into deep tissues, indicative of movement between cells during nutritive cell formation. In contrast, the Hessian fly proteins were primarily limited to the initially attacked cells in resistant plants. The limitation of effectors' spread in resistant plants was likely due to wall strengthening and rapid hypersensitive cell death. Cell death was found in in association with hypersensitive reaction triggered by the Family-1 effector SSGP-1A2. Our finding represents a significant progress in visualizing insect effectors in host tissues and mechanisms of plant resistance and susceptibility to gall midge pests.
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http://dx.doi.org/10.1002/pld3.246DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7428492PMC
August 2020

A new neuropeptide insect parathyroid hormone iPTH in the red flour beetle Tribolium castaneum.

PLoS Genet 2020 05 4;16(5):e1008772. Epub 2020 May 4.

Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.

In the postgenomics era, comparative genomics have advanced the understanding of evolutionary processes of neuropeptidergic signaling systems. The evolutionary origin of many neuropeptidergic signaling systems can be traced date back to early metazoan evolution based on the conserved sequences. Insect parathyroid hormone receptor (iPTHR) was previously described as an ortholog of vertebrate PTHR that has a well-known function in controlling bone remodeling. However, there was no sequence homologous to PTH sequence in insect genomes, leaving the iPTHR as an orphan receptor. Here, we identified the authentic ligand insect PTH (iPTH) for the iPTHR. The taxonomic distribution of iPTHR, which is lacking in Diptera and Lepidoptera, provided a lead for identifying the authentic ligand. We found that a previously described orphan ligand known as PXXXamide (where X is any amino acid) described in the cuttlefish Sepia officinalis has a similar taxonomic distribution pattern as iPTHR. Tests of this peptide, iPTH, in functional reporter assays confirmed the interaction of the ligand-receptor pair. Study of a model beetle, Tribolium castaneum, was used to investigate the function of the iPTH signaling system by RNA interference followed by RNA sequencing and phenotyping. The results suggested that the iPTH system is likely involved in the regulation of cuticle formation that culminates with a phenotype of defects in wing exoskeleton maturation at the time of adult eclosion. Moreover, RNAi of iPTHRs also led to significant reductions in egg numbers and hatching rates after parental RNAi.
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http://dx.doi.org/10.1371/journal.pgen.1008772DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224569PMC
May 2020

A Horizontal Gene Transfer Led to the Acquisition of a Fructan Metabolic Pathway in a Gall Midge.

Adv Biosyst 2020 04 21;4(4):e1900275. Epub 2020 Feb 21.

Department of Entomology, Kansas State University, 123 Waters Hall, Manhattan, KS, 66506, USA.

Animals are thought to use only glucose polymers (glycogen) as energy reserve, whereas both glucose (starch) and fructose polymers (fructans) are used by microbes and plants. Here, it is reported that the gall midge Mayetiola destructor, and likely other herbivorous animal species, gained the ability to utilize dietary fructans directly as storage polysaccharides by a single horizontal gene transfer (HGT) of bacterial levanase/inulinase gene followed by gene expansion and differentiation. Multiple genes encoding levanases/inulinases have their origin in a single HGT event from a bacterium and they show high expression levels and enzymatic activities in different tissues of the gall midge, including nondigestive fat bodies and eggs, both of which contained significant amounts of fructans. This study provides evidence that animals can also use fructans as energy reserve by incorporating bacterial genes in their genomes.
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http://dx.doi.org/10.1002/adbi.201900275DOI Listing
April 2020

Liquid water intake of the lone star tick, Amblyomma americanum: Implications for tick survival and management.

Sci Rep 2020 04 7;10(1):6000. Epub 2020 Apr 7.

Central European Institute of Technology, Center for Zoonoses, University of Veterinary and Pharmaceutical Sciences, Palackeho 1946/1, Brno, 612 42, Czech Republic.

Ixodid ticks are ectoparasites that feed exclusively on blood as their source of nutrients. Although ticks spend most of their life off the host, until now it has been assumed that the blood and the water vapor are the only sources of water to maintain water balance and prevent desiccation. Here we report for the first time that adult lone star ticks, Amblyomma americanum, also actively drink nutrient-free water, which greatly increases their survival. The volume of ingested water is greater in females than males (0.55 ± 0.06 vs 0.44 ± 0.07 µl) and most likely due to differences in tick size. Water uptake occurs through mouthparts and it can be later observed in the salivary glands and the midgut. We also exploited this behavior by adding a variety of inorganic compounds and microorganisms to water. Addition of inorganic salts to drinking water such as KHPO + NaCl+KNO resulted in 100% tick mortality within 3 days. As a proof of concept for using the water drinking as a delivery route of toxic reagents for ticks, we also show that adding Pseudomonas aeruginosa to drinking water quickly leads to tick death. This tick behavior can be exploited to target important physiological systems, which would make ticks vulnerable to dehydration and microbial dysbiosis.
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http://dx.doi.org/10.1038/s41598-020-63004-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7138852PMC
April 2020

Enhanced genome assembly and a new official gene set for Tribolium castaneum.

BMC Genomics 2020 Jan 14;21(1):47. Epub 2020 Jan 14.

Institut für Biowissenschaften, Universität Rostock, Albert-Einstein-Str. 3, 18059, Rostock, Germany.

Background: The red flour beetle Tribolium castaneum has emerged as an important model organism for the study of gene function in development and physiology, for ecological and evolutionary genomics, for pest control and a plethora of other topics. RNA interference (RNAi), transgenesis and genome editing are well established and the resources for genome-wide RNAi screening have become available in this model. All these techniques depend on a high quality genome assembly and precise gene models. However, the first version of the genome assembly was generated by Sanger sequencing, and with a small set of RNA sequence data limiting annotation quality.

Results: Here, we present an improved genome assembly (Tcas5.2) and an enhanced genome annotation resulting in a new official gene set (OGS3) for Tribolium castaneum, which significantly increase the quality of the genomic resources. By adding large-distance jumping library DNA sequencing to join scaffolds and fill small gaps, the gaps in the genome assembly were reduced and the N50 increased to 4753kbp. The precision of the gene models was enhanced by the use of a large body of RNA-Seq reads of different life history stages and tissue types, leading to the discovery of 1452 novel gene sequences. We also added new features such as alternative splicing, well defined UTRs and microRNA target predictions. For quality control, 399 gene models were evaluated by manual inspection. The current gene set was submitted to Genbank and accepted as a RefSeq genome by NCBI.

Conclusions: The new genome assembly (Tcas5.2) and the official gene set (OGS3) provide enhanced genomic resources for genetic work in Tribolium castaneum. The much improved information on transcription start sites supports transgenic and gene editing approaches. Further, novel types of information such as splice variants and microRNA target genes open additional possibilities for analysis.
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http://dx.doi.org/10.1186/s12864-019-6394-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6961396PMC
January 2020

Alpha-Gal and Cross-Reactive Carbohydrate Determinants in the N-Glycans of Salivary Glands in the Lone Star Tick, .

Vaccines (Basel) 2020 Jan 9;8(1). Epub 2020 Jan 9.

Complex Carbohydrate Center, University of Georgia, Athens, GA 30602, USA.

Ticks are important ectoparasites and vectors of numerous human and animal pathogens. Ticks secrete saliva that contains various bioactive materials to evade the host defense system, and often facilitates the pathogen transmission. In addition, the Lone star tick saliva is thought to be the sensitizer in red meat allergy that is characterized by an allergic reaction to glycan moieties carrying terminal galactose-alpha-1,3-galactose (aGal). To assess N-glycome of , we examined the N-glycan structures in male and female salivary glands at three different feeding stages and in carcasses of partially fed lone star ticks. We also surveyed the genes involved in the N-glycosylation in the tick species. The aGal epitopes and cross-reactive carbohydrate determinants (CCD) increases over time after the onset of blood feeding in both male and female . These CCDs include xylosylation of the core mannose, 1,3-mono and 1,3- and 1,6-difucosylations of the basal GlcNac and mono- or diantennary aGal. Combinations of both xylosylation and aGal and fucosylation and aGal were also found on the N-glycan structures. While the enzymes required for the early steps of the N-glycosylation pathway are quite conserved, the enzymes involved in the later stages of N-glycan maturation in the Golgi apparatus are highly diverged from those of insects. Most of all, we propose that the aGal serves as a molecular mimicry of bioactive proteins during tick feedings on mammalian hosts, while it contributes as a sensitizer of allergy in atypical host human.
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http://dx.doi.org/10.3390/vaccines8010018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7157712PMC
January 2020

CYP303A1 has a conserved function in adult eclosion in Locusta migratoria and Drosophila melanogaster.

Insect Biochem Mol Biol 2019 10 15;113:103210. Epub 2019 Aug 15.

Guangdong Provincial Key Laboratory of Insect Development Biology and Applied Technology, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou 510631, China. Electronic address:

Insect cytochrome P450 monooxygenases (CYPs) play essential roles in both xenobiotic metabolism and developmental processes. However, the exact physiological function of many CYP genes remains largely unknown. Screening the expression of the CYP genes from the CYP2 and mitochondrial CYP clans of Drosophila melanogaster revealed that Cyp303a1 is highly expressed in the pupal stage. Knockdown of CYP303A1 transcripts by RNAi using the Gal4/UAS system with a ubiquitous driver (tubulin-Gal4) in Drosophila or by dsRNA injection in the last nymph stage of Locusta migratoria resulted in severe defects in eclosion and lethality during and after adult emergence. In Drosophila, tissue-specific RNAi of Cyp303a1 with a wing-specific driver (MS1096-Gal4) revealed that Cyp303a1 was essential for wing extension. Stage-specific RNAi of Cyp303a1 using Gal80 for thermal-dependent-suppression found that the expression of Cyp303a1 at the middle pupal stage was absolutely required. Meanwhile, Cyp303a1 mutants exhibited more than 80% lethality at the late embryonic development stages. Embryonic lethality of the Cyp303a1 mutants was fully rescued by the ubiquitous overexpression of exogenous Cyp303a1. Taken together, we conclude that Cyp303a1 is indispensable for embryonic development and adult eclosion in D. melanogaster, the latter role being conserved over 400 million years of insect evolution.
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http://dx.doi.org/10.1016/j.ibmb.2019.103210DOI Listing
October 2019

Ultrastructural mapping of salivary gland innervation in the tick Ixodes ricinus.

Sci Rep 2019 05 2;9(1):6860. Epub 2019 May 2.

UMR BIPAR, INRA, Ecole Nationale Vétérinaire d'Alfort, ANSES, Université Paris-Est, Maisons-Alfort, France.

The salivary gland of hard ticks is a highly innervated tissue where multiple intertwined axonal projections enter each individual acini. In the present study, we investigated the ultrastructural architecture of axonal projections within granular salivary gland type II and III acini of Ixodes ricinus female. Using immunogold labeling, we specifically examined the associations of SIFamide neuropeptide, SIFamide receptor (SIFa_R), neuropeptide pigment dispersing factor (PDF), and the invertebrate-specific D1-like dopamine receptor (InvD1L), with acinar cells. In both acini types, SIFamide-positive axons were found to be in direct contact with either basal epithelial cells or a single adlumenal myoepithelial cell in close proximity to the either the acinar duct or its valve, respectively. Accordingly, SIFa_R staining correlated with SIFamide-positive axons in both basal epithelial and myoepithelial cells. Immunoreactivity for both InvD1L and PDF (type II acini exclusively) revealed positive axons radiating along the acinar lumen. These axons were primarily enclosed by the adlumenal myoepithelial cell plasma membrane and interstitial projections of ablumenal epithelial cells. Our study has revealed the detailed ultrastructure of I. ricinus salivary glands, and provides a solid baseline for a comprehensive understanding of the cell-axon interactions and their functions in this essential tick organ.
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http://dx.doi.org/10.1038/s41598-019-43284-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6497691PMC
May 2019

The Ecdysis Triggering Hormone System, via ETH/ETHR-B, Is Essential for Successful Reproduction of a Major Pest Insect, (Hendel).

Front Physiol 2019 18;10:151. Epub 2019 Mar 18.

Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.

Ecdysis triggering hormone (ETH), released by the Inka cells, is a master hormone in regulating the ecdysis process in insect. Here we investigated the presence and role of the ETH signaling in the female adult of the oriental fruit fly, (Hendel) that is one of the most important invasive pest insects in agriculture worldwide. In the female adult, ETH was confirmed in the Inka cells at the tracheae by immunostaining and also exposure to ETH stimulated the isolated corpora allata of adult in activity. Then we prepared cDNA of females at 0, 5, 10, 15, and 20 days after adult eclosion, and RT-qPCR showed that the expression pattern of and its receptor started from a peak at the day of adult eclosion (day 0), then dropped to basal levels and increased again between day 10 and 15 which is also the period corresponding to ovary growth. In contrast, was absent with Ct values of >33. The expression patterns of the ecdysteroid-producing Halloween genes and , and the vitellogenin genes , , and co-occurred with peak levels at days 10-15, and also juvenile hormone acid methyltransferase () showed increased levels on day 15. Further in RNAi assays to better understand the role of ETH and ETHR, dsRNA was injected to adult and this led to a respective decrease in expression of 62 and 56% for and , while stayed absent with Ct values of 33. In these RNAi-females, there was an apparently decreased expression for and , together with a significant decrease of the JH titer and egg production. Injection of the JH mimetic methoprene could rescue expression and egg production. Upstream, in ds/ds-injected females, 20-hydroxyecdysone (20E) injection rescued the transcriptions of and and also egg production. In summary, our results shed more light on the pivotal role that the ETH peptide hormone and its receptor ETHR-B play an essential role in the reproduction of the female adult of , via the regulation of JH and vitellogenin, which are controlled by a pulse of 20E.
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http://dx.doi.org/10.3389/fphys.2019.00151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6431669PMC
March 2019

Dissecting Flavivirus Biology in Salivary Gland Cultures from Fed and Unfed (Black-Legged Tick).

mBio 2019 01 29;10(1). Epub 2019 Jan 29.

Biology of Vector-Borne Viruses Section, Laboratory of Virology, Rocky Mountain Laboratories, NIAID/NIH, Hamilton, Montana, USA.

The tick transmits a number of pathogens, including tick-borne flaviviruses (TBFVs). In the United States, confirmed human infections with the Powassan virus (POWV) TBFV have a fatality rate of ∼10% and are increasing in incidence. Tick salivary glands (SGs) serve as an organ barrier to TBFV transmission, and little is known regarding the location of TBFV infection in SGs from fed ticks. Previous studies showed vanin () involved with TBFV infection of ISE6 embryonic cells, suggesting a potential role for this gene. The overall goal of this study was to use SG cultures to compare data on TBFV biology in SGs from fully engorged, replete (fed) ticks and from unfed ticks. TBFV multiplication was higher in SGs from fed ticks than in those from unfed ticks. Virus-like particles were observed only in granular acini of SGs from unfed ticks. The location of TBFV infection of SGs from fed ticks was observed in cells lining lobular ducts and trachea but not observed in acini. Transcript knockdown of decreased POWV multiplication in infected SG cultures from both fed and unfed ticks. This work was the first to identify localization of TBFV multiplication in SG cultures from a fed tick and a tick transcript important for POWV multiplication in the tick SG, an organ critical for TBFV transmission. This research exemplifies the use of SG cultures in deciphering TBFV biology in the tick and as a translational tool for screening and identifying potential tick genes as potential countermeasure targets. Tick-borne flaviviruses (TBFVs) are responsible for more than 15,000 human disease cases each year, and Powassan virus lineage 2 (POWV-L2) deer tick virus has been a reemerging threat in North America over the past 20 years. Rapid transmission of TBFVs in particular emphasizes the importance of preventing tick bites, the difficulty in developing countermeasures to prevent transmission, and the importance of understanding TBFV infection in tick salivary glands (SGs). Tick blood feeding is responsible for phenomenal physiological changes and is associated with changes in TBFV multiplication within the tick and in SGs. Using SG cultures from female ticks, the primary aims of this study were to identify cellular localization of virus-like particles in acini of infected SGs from fed and unfed ticks, localization of TBFV infection in infected SGs from fed ticks, and a tick transcript (with associated metabolic function) involved in POWV-L2 infection in SG cultures.
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http://dx.doi.org/10.1128/mBio.02628-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6355982PMC
January 2019

A Versatile Model of Hard Tick Infestation on Laboratory Rabbits.

J Vis Exp 2018 10 6(140). Epub 2018 Oct 6.

Unité Mixte de Recherche (UMR) Biologie moléculaire et immunologie parasitaires (BIPAR), Institut national de la recherche agronomique (INRA), Ecole Nationale Vétérinaire d'Alfort, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Université Paris-Est;

The use of live animals in tick research is crucial for a variety of experimental purposes including the maintenance of hard tick colonies in the laboratory. In ticks, all developmental stages (except egg) are hematophagous, and acquiring a blood-meal when attached to their vertebrate hosts is essential for the successful completion of their life cycle. Here we demonstrate a simple method that uses easily openable capsules for feeding of hard ticks on rabbits. The advantages of the proposed method include its simplicity, short duration and most importantly versatile adjustment to the needs of specific experimental requirements. The method makes possible the use of multiple chambers (of various sizes) on the same animal, which permits feeding of multiple stages or different experimental groups while reducing the overall animal requirement. The non-irritating and easily accessible materials used minimizes discomfort to the animals, which can be easily recovered from an experiment and offered for adoption or reused if the ethical protocol allows it.
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http://dx.doi.org/10.3791/57994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6235438PMC
October 2018

Endocrine system in supernumerary molting of the flour beetle, Tribolium freemani, under crowded conditions.

Insect Biochem Mol Biol 2018 10 24;101:76-84. Epub 2018 Aug 24.

Department of Entomology, Kansas State University, Manhattan, KS, 66506, United States. Electronic address:

In the flour beetle, Tribolium freemani, a crowded environment in the last larval instar delays the development into a pupa, but the beetle continues to engage in larval-larval molting, which is an adaptive response to avoid being the victim of cannibalism as an immobile pupa. To understand the endocrine mechanism involved in this developmental process, we investigated the components of the juvenile hormone and ecdysone signaling systems. We examined whether elevated juvenile hormone levels in the crowded condition is the sole causal factor for the supernumerary molting. RNA interference (RNAi) of the JH acid methyltransferase (TfMT3) for lowering juvenile hormone titer in the crowded condition could not rescue pupation and instead resulted in lethality with developmental arrest at the prepupal stage. Kruppel-homolog 1 (TfKr-h1), the immediate downstream JH signal, was highly upregulated even in the RNAi of TfMT3 in a crowded condition. RNAi of TfKr-h1 resulted in a phenocopy of the lethal TfMT3 RNAi in a crowded condition. In addition, RNAi of TfMT3 in a crowded condition resulted in lack of the major ecdysone peak in the prepupal stage. We conclude that while a crowded condition induces supernumerary molts by elevating juvenile hormone levels, it can also inhibit metamorphosis by disrupting additional endocrine processes. The current study suggests that crowded conditions affect multiple independent factors in the endocrine and the downstream signaling systems.
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http://dx.doi.org/10.1016/j.ibmb.2018.08.002DOI Listing
October 2018

Neural and endocrine regulation of osmoregulatory organs in tick: Recent discoveries and implications.

Gen Comp Endocrinol 2019 07 2;278:42-49. Epub 2018 Aug 2.

Kansas State University, Department of Entomology, Kansas State University, Manhattan, KS 66504, USA. Electronic address:

Ticks can survive in harsh and fluctuating vegetated environments for long durations between blood feedings with highly developed osmoregulatory mechanisms. Like the unique life history of hematophagous ticks, osmoregulatory organs and their regulatory mechanisms are significantly different from those in the closely related insect taxa. Over the last ten years, research has uncovered several neuropeptidergic innervations of the primary osmoregulatory organ, the salivary glands: myoinhibitory peptide (MIP), SIFamide, and elevenin. These neuropeptides are thought to be modulators of dopamine's autocrine or paracrine actions controlling the salivary glands, including the activation of fluid transport into the lumen of salivary acini and the pumping and gating action of salivary acini for expelling fluids out into salivary ducts. These actions are through two different dopamine receptors, D1 receptor and invertebrate D1-like dopamine receptor, respectively. Interestingly, MIP and SIFamide are also involved in the control of another important excretory/osmoregulatory organ, the hindgut, where SIFamide is myostimulatory, with MIP having antagonistic effects. FGLamide related allatostatin is also found to have axonal projections located on the surface of the rectum. Investigations of the osmoregulatory mechanisms of these critical vector species will potentially lead to the development of a measure to control tick species.
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http://dx.doi.org/10.1016/j.ygcen.2018.08.004DOI Listing
July 2019

Molecular characterization of neuropeptide elevenin and two elevenin receptors, IsElevR1 and IsElevR2, from the blacklegged tick, Ixodes scapularis.

Insect Biochem Mol Biol 2018 10 31;101:66-75. Epub 2018 Jul 31.

Kansas State University, 123 Waters Hall, Manhattan, KS66504, USA. Electronic address:

Understanding salivation in hematophagous arthropod vectors is crucial to developing novel methods to prevent vector-borne disease transmission. The interactions between the tick, host, and pathogens during salivation are highly complex, and are dynamically regulated by the tick central nervous system (synganglion). Recently, tick salivary modulation via neuropeptides was highlighted by mapping neuropeptidergic cells in the synganglion and salivary glands in hard ticks. In this study, we characterized the role of a novel neuropeptide, elevenin (IsElev), and its receptors (IsElevR1 and IsElevR2) in the innervation of the salivary glands from Ixodes scapularis female ticks. Homology-based BLAST searches of the I. scapularis genome and Sequence Read Archive (SRA), followed by gene cloning, identified candidate genes: IsElev, IsElevR1, and IsElevR2. The IsElev candidate contained common elevenin features: a signal peptide immediately before an elevenin precursor and two cysteines. During functional assays, synthetic IsElev efficiently activated both IsElevR1 and IsElevR2, as indicated by elevated calcium mobilization. IsElevR1 (EC: 0.01 nM) was about 560 times more sensitive to synthetic IsElev than IsElevR2 (EC: 5.59 nM). Immunoreactivity (IR) for IsElev and IsElevR1 was detected as a complex neuronal projection and several neurons in the synganglion. In salivary glands, IsElev-IR was detected in an axonal projection on the surface of the main salivary duct and in axon terminals within type II/III salivary gland acini, which are colocalized with SIFamide-IR. IsElevR1-IR was detected on the luminal surface of both type II/III acini. IsElev transcript levels were high in the synganglion and reached a peak at day 5 post-blood feeding. Salivary glands expressed IsElevR1, which gradually increased over the course of blood feeding until repletion. Here, we propose that IsElev and IsElevR1, localized in salivary gland acini types II/III, are likely involved in tick salivary secretion in the rapid engorgement phase of tick feeding. In addition, we also provide the evidences for IsElev action on the ovary by showing IsElevR1-IR and IsElevR2-IR on the surface of ovary.
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http://dx.doi.org/10.1016/j.ibmb.2018.07.005DOI Listing
October 2018

Molecular mechanisms influencing efficiency of RNA interference in insects.

Pest Manag Sci 2019 Jan 13;75(1):18-28. Epub 2018 Aug 13.

Department of Entomology, Kansas State University, Manhattan, KS, USA.

RNA interference (RNAi) is an endogenous, sequence-specific gene-silencing mechanism elicited by small RNA molecules. RNAi is a powerful reverse genetic tool, and is currently being utilized for managing insects and viruses. Widespread implementation of RNAi-based pest management strategies is currently hindered by inefficient and highly variable results when different insect species, strains, developmental stages, tissues, and genes are targeted. Mechanistic studies have shown that double-stranded ribonucleases (dsRNases), endosomal entrapment, deficient function of the core machinery, and inadequate immune stimulation contribute to limited RNAi efficiency. However, a comprehensive understanding of the molecular mechanisms limiting RNAi efficiency remains elusive. Recent advances in dsRNA stability in physiological tissues, dsRNA internalization into cells, the composition and function of the core RNAi machinery, as well as small-interfering RNA/double-stranded RNA amplification and spreading mechanisms are reviewed to establish a global understanding of the obstacles impeding wider understanding of RNAi mechanisms in insects. © 2018 Society of Chemical Industry.
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http://dx.doi.org/10.1002/ps.5126DOI Listing
January 2019

Corazonin Signaling Is Required in the Male for Sperm Transfer in the Oriental Fruit Fly .

Front Physiol 2018 4;9:660. Epub 2018 Jun 4.

Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing, China.

Corazonin (Crz) is a widely distributed neuropeptide (or neurohormone) in insects with diverse physiological functions. The present study aimed to reveal the functions of Crz and its receptor (CrzR) in the regulation of sexual behavior and fertility in male . Tissue-specific expression analyses showed that the transcript was most abundant in the central nervous system (CNS), and the transcript was most abundant in both the fat body and CNS. Immunochemical localization confirmed that three pairs of Crz-immunoreactive neurons are located in the dorsolateral protocerebrum region of male adult brain. Importantly, RNAi-mediated Crz knockdown lengthened mating duration in males, and knockdown of Crz or CrzR strongly decreased male fertility in the following 3 days, while the courtship behavior and mating efficiency were not affected. The reduced number of sperm in the reproductive organs of mated females indicated that Crz knockdown in males reduced sperm transfer. The findings of this study indicate that Crz contributes to the reproductive physiology of the oriental fruit fly by regulating sperm transfer in male adults.
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http://dx.doi.org/10.3389/fphys.2018.00660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994612PMC
June 2018

Water absorption through salivary gland type I acini in the blacklegged tick, .

PeerJ 2017 31;5:e3984. Epub 2017 Oct 31.

Department of Entomology, Kansas State University, Manhattan, KS, United States of America.

Tick salivary glands play critical roles in maintaining water balance for survival, as they eliminate excess water and ions during blood feeding on hosts. In the long duration of fasting in the off-host period, ticks secrete hygroscopic saliva into the mouth cavity to uptake atmospheric water vapor. Type I acini of tick salivary glands are speculated to be involved in secretion of hygroscopic saliva based on ultrastructure studies. However, we recently proposed that type I acini play a role in resorption of water/ions from the primary saliva produced by other salivary acini (i.e., types II and III) during the tick blood feeding phase. In this study, we tested the function of type I acini in unfed female . The route of ingested water was tracked after forced feeding of water with fluorescent dye rhodamine123. We found that type-I acini of the salivary glands, but not type II and III, are responsible for water uptake. In addition, the ingestion of water through the midgut was also observed. Injection or feeding of ouabain, a Na/K-ATPase inhibitor, suppressed water absorption in type I acini. When was offered a droplet of water, ticks rarely imbibed water directly (5%), while some approached the water droplet to use the high humidity formed in the vicinity of the droplet (23%). We conclude that during both on- and off-host stages, type I acini in salivary glands of female absorb water and ions.
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http://dx.doi.org/10.7717/peerj.3984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5669254PMC
October 2017

Multifaceted biological insights from a draft genome sequence of the tobacco hornworm moth, Manduca sexta.

Insect Biochem Mol Biol 2016 09 12;76:118-147. Epub 2016 Aug 12.

Centre of Systems Biology, Biomedical Research Foundation, Academy of Athens, Athens, Greece.

Manduca sexta, known as the tobacco hornworm or Carolina sphinx moth, is a lepidopteran insect that is used extensively as a model system for research in insect biochemistry, physiology, neurobiology, development, and immunity. One important benefit of this species as an experimental model is its extremely large size, reaching more than 10 g in the larval stage. M. sexta larvae feed on solanaceous plants and thus must tolerate a substantial challenge from plant allelochemicals, including nicotine. We report the sequence and annotation of the M. sexta genome, and a survey of gene expression in various tissues and developmental stages. The Msex_1.0 genome assembly resulted in a total genome size of 419.4 Mbp. Repetitive sequences accounted for 25.8% of the assembled genome. The official gene set is comprised of 15,451 protein-coding genes, of which 2498 were manually curated. Extensive RNA-seq data from many tissues and developmental stages were used to improve gene models and for insights into gene expression patterns. Genome wide synteny analysis indicated a high level of macrosynteny in the Lepidoptera. Annotation and analyses were carried out for gene families involved in a wide spectrum of biological processes, including apoptosis, vacuole sorting, growth and development, structures of exoskeleton, egg shells, and muscle, vision, chemosensation, ion channels, signal transduction, neuropeptide signaling, neurotransmitter synthesis and transport, nicotine tolerance, lipid metabolism, and immunity. This genome sequence, annotation, and analysis provide an important new resource from a well-studied model insect species and will facilitate further biochemical and mechanistic experimental studies of many biological systems in insects.
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http://dx.doi.org/10.1016/j.ibmb.2016.07.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5010457PMC
September 2016

Mechanistic insights into the first Lygus-active β-pore forming protein.

Arch Biochem Biophys 2016 06 19;600:1-11. Epub 2016 Mar 19.

Monsanto Company, Chesterfield, MO, USA.

The cotton pests Lygus hesperus and Lygus lineolaris can be controlled by expressing Cry51Aa2.834_16 in cotton. Insecticidal activity of pore-forming proteins is generally associated with damage to the midgut epithelium due to pores, and their biological specificity results from a set of key determinants including proteolytic activation and receptor binding. We conducted mechanistic studies to gain insight into how the first Lygus-active β-pore forming protein variant functions. Biophysical characterization revealed that the full-length Cry51Aa2.834_16 was a stable dimer in solution, and when exposed to Lygus saliva or to trypsin, the protein underwent proteolytic cleavage at the C-terminus of each of the subunits, resulting in dissociation of the dimer to two separate monomers. The monomer showed tight binding to a specific protein in Lygus brush border membranes, and also formed a membrane-associated oligomeric complex both in vitro and in vivo. Chemically cross-linking the β-hairpin to the Cry51Aa2.834_16 body rendered the protein inactive, but still competent to compete for binding sites with the native protein in vivo. Our study suggests that disassociation of the Cry51Aa2.834_16 dimer into monomeric units with unoccupied head-region and sterically unhindered β-hairpin is required for brush border membrane binding, oligomerization, and the subsequent steps leading to insect mortality.
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http://dx.doi.org/10.1016/j.abb.2016.03.016DOI Listing
June 2016

Multiple functions of Na/K-ATPase in dopamine-induced salivation of the Blacklegged tick, Ixodes scapularis.

Sci Rep 2016 Feb 10;6:21047. Epub 2016 Feb 10.

Department of Entomology, Kansas State University, 123 Waters Hall, Manhattan, KS 66506, USA.

Control of salivary secretion in ticks involves autocrine dopamine activating two dopamine receptors: D1 and Invertebrate-specific D1-like dopamine receptors. In this study, we investigated Na/K-ATPase as an important component of the secretory process. Immunoreactivity for Na/K-ATPase revealed basal infolding of lamellate cells in type-I, abluminal interstitial (epithelial) cells in type-II, and labyrinth-like infolding structures opening towards the lumen in type-III acini. Ouabain (10 μmol l(-1)), a specific inhibitor of Na/K-ATPase, abolished dopamine-induced salivary secretion by suppressing fluid transport in type III acini. At 1 μmol l(-1), ouabain, the secreted saliva was hyperosmotic. This suggests that ouabain also inhibits an ion resorptive function of Na/K-ATPase in the type I acini. Dopamine/ouabain were not involved in activation of protein secretion, while dopamine-induced saliva contained constitutively basal level of protein. We hypothesize that the dopamine-dependent primary saliva formation, mediated by Na/K-ATPase in type III and type II acini, is followed by a dopamine-independent resorptive function of Na/K-ATPase in type I acini located in the proximal end of the salivary duct.
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http://dx.doi.org/10.1038/srep21047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4748274PMC
February 2016

Genomic insights into the Ixodes scapularis tick vector of Lyme disease.

Nat Commun 2016 Feb 9;7:10507. Epub 2016 Feb 9.

Department of Medicine, Division of Infectious Diseases, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.

Ticks transmit more pathogens to humans and animals than any other arthropod. We describe the 2.1 Gbp nuclear genome of the tick, Ixodes scapularis (Say), which vectors pathogens that cause Lyme disease, human granulocytic anaplasmosis, babesiosis and other diseases. The large genome reflects accumulation of repetitive DNA, new lineages of retro-transposons, and gene architecture patterns resembling ancient metazoans rather than pancrustaceans. Annotation of scaffolds representing ∼57% of the genome, reveals 20,486 protein-coding genes and expansions of gene families associated with tick-host interactions. We report insights from genome analyses into parasitic processes unique to ticks, including host 'questing', prolonged feeding, cuticle synthesis, blood meal concentration, novel methods of haemoglobin digestion, haem detoxification, vitellogenesis and prolonged off-host survival. We identify proteins associated with the agent of human granulocytic anaplasmosis, an emerging disease, and the encephalitis-causing Langat virus, and a population structure correlated to life-history traits and transmission of the Lyme disease agent.
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http://dx.doi.org/10.1038/ncomms10507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4748124PMC
February 2016

Ligand selectivity in tachykinin and natalisin neuropeptidergic systems of the honey bee parasitic mite Varroa destructor.

Sci Rep 2016 Jan 28;6:19547. Epub 2016 Jan 28.

Department of Entomology, Kansas State University, Manhattan, Kansas 66506, United States.

The varroa mite, Varroa destructor, is a devastating ectoparasite of the honey bees Apis mellifera and A. cerana. Control of these mites in beehives is a challenge in part due to the lack of toxic agents that are specific to mites and not to the host honey bee. In searching for a specific toxic target of varroa mites, we investigated two closely related neuropeptidergic systems, tachykinin-related peptide (TRP) and natalisin (NTL), and their respective receptors. Honey bees lack both NTL and the NTL receptor in their genome sequences, providing the rationale for investigating these receptors to understand their specificities to various ligands. We characterized the receptors for NTL and TRP of V. destructor (VdNTL-R and VdTRP-R, respectively) and for TRP of A. mellifera (AmTRP-R) in a heterologous reporter assay system to determine the activities of various ligands including TRP/NTL peptides and peptidomimetics. Although we found that AmTRP-R is highly promiscuous, activated by various ligands including two VdNTL peptides when a total of 36 ligands were tested, we serendipitously found that peptides carrying the C-terminal motif -FWxxRamide are highly specific to VdTRP-R. This motif can serve as a seed sequence for designing a VdTRP-R-specific agonist.
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http://dx.doi.org/10.1038/srep19547DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4730192PMC
January 2016