Tick Sweats

Ticks are obligatory ectoparasites of many vertebrate hosts including human. Osmoregulatory functions of ticks are crucial for the survival, especially, in the off-host ticks in arid area. We found that injection of water in the body cavity of tick immediately triggers excretion of solution through the exoskeletal cuticles, like sweating. This response occurred in a bilateral asymmetric manner; the injection on left side of the body induced the sweating on only the left half, while the injection into right side did not induce sweat. The sweating response was reduced in the injections of high osmolar Naci (1 M). This is the first description of sweating physiology in maintenance of water homeostasis in the Lone star tick

Bioactivities of Proctolin Mimetic in Drosophila melanogaster

The insect neuropeptide proctolin was originally purified for its myotropic actions on insect hindguts, however it has been shown to be distributed widely throughout arthropods. This pentapeptide, RYLPT or Arg-Tyr-Leu-Pro-Thr, is highly conserved across arthropod species. We were interested in whether observable bioactivity, physiological and behavioral changes, occurs upon the injections of proctolin or proctolin mimetic peptides. We found strong activities of proctolin and proctolin mimetic in immediate inductions of proboscis behavior and defecation. Peptidomimetics showed strong activities opening a new revenue for development of new class of insecticidal compound

Can the Gram-negative bacterium Escherichia coli colonize the gut of Lone Star Tick (Amblyomma americanum)?

Ticks are obligate blood feeding ectoparasites and vectors of several mammalian pathogens (Williams-Newkirk et al, 2014). In addition to pathogens they also carry a bacterial community with commensal and symbiotic relationships (Bonnet et al, 2017). Using a culture-dependent approach we previously reported a high prevalence of Gram-positive bacteria in the gut of field collected lone star ticks (Amblyomma americanum). These results suggested that epithelial immunity functions to control Gram-negative bacteria in A. americanum. In this study, we used a culturing and non-culturing approach to measure the outcome of E.coli (Gram-negative) when fed to female adult lone star ticks (n=16). Results showed a significant reduction of E.coli at Days 1, 3 and 7 post bacterial feeding. qPCR of 16S rDNA confirmed reduction of bacterial rDNA when compared to water fed ticks (n=16). Our results suggest that there is a midgut epithelial immune response in place, which mainly targets Gram-negative bacteria

Investigation of the Functions of Insect Arginine Vasopressin-like Peptides

Citation: Tokach, R. (2017). Investigation of the Functions of Insect Arginine Vasopressin-like Peptides . 1st Annual Undergraduate Research Experience in Entomology Symposium, November 16, 2016. Manhattam, KS.The neuropeptide arginine vasopressin (AVP) is a multifunctional signaling peptide that is highly conserved across eukaryotic animals. In mammals, it primarily acts as an anti-diuretic and a regulator of blood pressure. These traits among others merit the study of the arginine vasopressin-like (AVPL) hormone found in insects (Aikins et al., 2008). We investigated the bioactivity of AVPL in an assay measuring the recovery time after knockout in water, indicating hormonal activity for alert states in the red flour beetle Tribolium castaneum. We found that injections of an AVPL mimetic peptide (AVP1) prolonged the knockout time, implying that the AVPL causes longer suppression of the recovery from water shock

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

Citation: Kim, D., Urban, J., Boyle, D. L., & Park, Y. (2016). Multiple functions of Na/K-ATPase in dopamine-induced salivation of the Blacklegged tick, Ixodes scapularis. Scientific Reports, 6, 13. doi:10.1038/srep21047Control 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 mu mol l(-1)), a specific inhibitor of Na/K-ATPase, abolished dopamine-induced salivary secretion by suppressing fluid transport in type III acini. At 1 mu mol 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

Genetics of a Transgenic Beetle (Tribolium castaneum) Carrying Green Fluorescent Protein

We found that a transgenic line of Tribolium castaneum, previously characterized for the expression of green fluorescent protein (GFP) in the oenocyte (OE strain), shows unusual genetics based on the GFP expression patterns. The larval individuals of OE line showed GFP expressions are not homogeneous among individuals; the expressions are in their oenocyte or hindgut, or in both organs. We provide two alternative hypotheses for this phenomenon: H1) variable expressions of a GFP gene in different stages or H2) more than one GFP transgenes. We tested this hypotheses by examining the GFP expression patterns in larval stages over the period of one week. In addition, we crossed the OE line to wildtype to understand the segregation pattern of the GFP phenotypes. We found that the GFP expression pattern in the OE changes within a molting instar leading to an conclusion accepting the H2) variable expressions of a GFP transgene in OE line, while the genetic crossing is in progress to test the H1) multiple GFP transgene insertions

Individual differences in impulsive and risky choice: effects of environmental rearing conditions

The present experiment investigated early-rearing environment modulation of individual differences in impulsive and risky choice. Rats were reared in an isolated condition (IC; n = 12), in which they lived alone without novel stimuli, or an enriched condition (EC; n = 12), in which they lived among conspecifics with novel stimuli. The impulsive choice task involved choices between smaller-sooner (SS) versus larger-later (LL) rewards. The risky choice task involved choices between certain-smaller (C-S) versus uncertain-larger (U-L) rewards. Following choice testing, incentive motivation to work for food was measured using a progressive ratio task and correlated with choice behavior. HPLC analyses were conducted to determine how monoamine concentrations within the prefrontal cortex (PFC) and nucleus accumbens (NAC) related to behavior in different tasks. IC rats were more impulsive than EC rats, but they did not differ in risky choice behavior. However, choice behavior across tasks was significantly correlated (i.e., the more impulsive rats were also riskier). There were no group differences in monoamine levels, but noradrenergic and serotonergic concentrations were significantly correlated with impulsive and risky choice. Furthermore, serotonin and norepinephrine concentrations in the NAC significantly correlated with incentive motivation and the timing of the reward delays within the choice tasks. These results suggest a role for domain general processes in impulsive and risky choice and indicate the importance of the NAC and/or PFC in timing, reward processing, and choice behavior

The Tribolium castaneum cell line TcA: a new tool kit for cell biology

The red flour beetle, Tribolium castaneum, is an agriculturally important insect pest that has been widely used as a model organism. Recently, an adherent cell line (BCIRL-TcA-CLG1 or TcA) was developed from late pupae of the red flour beetle. Next generation transcriptome sequencing of TcA cells demonstrated expression of a wide variety of genes associated with specialized functions in chitin metabolism, immune responses and cellular and systemic RNAi pathways. Accordingly, we evaluated the sensitivity of TcA cells to dsRNA to initiate an RNAi response. TcA cells were highly sensitive to minute amounts of dsRNA, with a minimum effective dose of 100 pg/mL resulting in significant suppression of gene expression. We have also developed a plasmid containing two TcA-specific promoters, the promoter from the 40S ribosomal protein subunit (TC006550) and a bi-directional heat shock promoter (TcHS70) from the intergenic space between heat shock proteins 68a and b. These promoters have been employed to provide high levels of either constitutive (TC006550) or inducible (TcHS70) gene expression of the reporter proteins. Our results show that the TcA cell line, with its sensitivity to RNAi and functional TcA-specific promoters, is an invaluable resource for studying basic molecular and physiological questions

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

Citation: Jiang, H., Kim, D., Dobesh, S., Evans, J. D., Nachman, R. J., Kaczmarek, K., . . . Park, Y. (2016). Ligand selectivity in tachykinin and natalisin neuropeptidergic systems of the honey bee parasitic mite Varroa destructor. Scientific Reports, 6, 8. doi:10.1038/srep19547The 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

Alpha-gal and cross-reactive carbohydrate determinants in the N-glycans of salivary glands in the lone star tick, Amblyomma americanum

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 Amblyomma americanum, 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 A. americanum. 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