Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 52
Filter
Add more filters










Publication year range
1.
J Cell Physiol ; 2024 Apr 30.
Article in English | MEDLINE | ID: mdl-38685860

ABSTRACT

Galectin-12 is a tissue-specific galectin that has been largely defined by its role in the regulation of adipocyte differentiation and lipogenesis. This study aimed to evaluate the role of galectin-12 in the differentiation and polarization of neutrophils within a model of acute myeloid leukemia HL-60 cells. All-trans retinoic acid and dimethyl sulfoxide were used to induce differentiation of HL-60 cells which led to the generation of two phenotypes of neutrophil-like cells with opposite changes in galectin-12 gene (LGALS12) expression and different functional responses to N-formyl- l-methionyl- l-leucyl- l-phenylalanine. These phenotypes showed significant differences of differentially expressed genes on a global scale based on bioinformatics analysis of available Gene Expression Omnibus (GEO) data sets. We also demonstrated that HL-60 cells could secrete and accumulate galectin-12 in cell culture medium under normal growth conditions. This secretion was found to be entirely inhibited upon neutrophilic differentiation and was accompanied by an increase in intracellular lipid droplet content and significant enrichment of 22 lipid gene ontology terms related to lipid metabolism in differentiated cells. These findings suggest that galectin-12 could serve as a marker of neutrophilic plasticity or polarization into different phenotypes and that galectin-12 secretion may be influenced by lipid droplet biogenesis.

2.
Sci Rep ; 13(1): 19343, 2023 11 07.
Article in English | MEDLINE | ID: mdl-37935795

ABSTRACT

Energy metabolism is a highly conserved process that balances generation of cellular energy and maintenance of redox homeostasis. It consists of five interconnected pathways: glycolysis, tricarboxylic acid cycle, pentose phosphate, trans-sulfuration, and NAD+ biosynthesis pathways. Environmental stress rewires cellular energy metabolism. Type-2 diabetes is a well-studied energy metabolism rewiring state in human pancreatic ß-cells where glucose metabolism is uncoupled from insulin secretion. The two-spotted spider mite, Tetranychus urticae (Koch), exhibits a remarkable ability to adapt to environmental stress. Upon transfer to unfavourable plant hosts, mites experience extreme xenobiotic stress that dramatically affects their survivorship and fecundity. However, within 25 generations, mites adapt to the xenobiotic stress and restore their fitness. Mites' ability to withstand long-term xenobiotic stress raises a question of their energy metabolism states during host adaptation. Here, we compared the transcriptional responses of five energy metabolism pathways between host-adapted and non-adapted mites while using responses in human pancreatic islet donors to model these pathways under stress. We found that non-adapted mites and human pancreatic ß-cells responded in a similar manner to host plant transfer and diabetogenic stress respectively, where redox homeostasis maintenance was favoured over energy generation. Remarkably, we found that upon host-adaptation, mite energy metabolic states were restored to normal. These findings suggest that genes involved in energy metabolism can serve as molecular markers for mite host-adaptation.


Subject(s)
Host Adaptation , Tetranychidae , Animals , Humans , Tetranychidae/genetics , Xenobiotics , Energy Metabolism
3.
Plant Physiol ; 193(4): 2605-2621, 2023 Nov 22.
Article in English | MEDLINE | ID: mdl-37437113

ABSTRACT

Composite generalist herbivores are comprised of host-adapted populations that retain the ability to shift hosts. The degree and overlap of mechanisms used by host-adapted generalist and specialist herbivores to overcome the same host plant defenses are largely unknown. Tetranychidae mites are exceptionally suited to address the relationship between host adaptation and specialization in herbivores as this group harbors closely related species with remarkably different host ranges-an extreme generalist the two-spotted spider mite (Tetranychus urticae Koch [Tu]) and the Solanaceous specialist Tetranychus evansi (Te). Here, we used tomato-adapted two-spotted spider mite (Tu-A) and Te populations to compare mechanisms underlying their host adaptation and specialization. We show that both mites attenuate induced tomato defenses, including protease inhibitors (PIs) that target mite cathepsin L digestive proteases. While Te solely relies on transcriptional attenuation of PI induction, Tu and Tu-A have elevated constitutive activity of cathepsin L proteases, making them less susceptible to plant anti-digestive proteins. Tu-A and Te also rely on detoxification of tomato constitutive defenses. Te uses esterase and P450 activities, while Tu-A depends on the activity of all major detoxification enzymatic classes to disarm tomato defensive compounds to a lesser extent. Thus, even though both Tu-A and Te use similar mechanisms to counteract tomato defenses, Te can better cope with them. This finding is congruent with the ecological and evolutionary times required to establish mite adaptation and specialization states, respectively.


Subject(s)
Tetranychidae , Animals , Host Adaptation , Cathepsin L , Plants , Biological Evolution , Herbivory
4.
Phytochemistry ; 206: 113529, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36473515

ABSTRACT

Suberin deposition involves both phenolic and aliphatic polymer biosynthesis and deposition in the same tissue. Therefore, any consideration of exploiting suberin for crop enhancement (e.g., enhanced storage, soil borne disease resistance) requires knowledge of both phenolic and aliphatic component biosynthesis and their coordinated, temporal deposition. In the present study, we use a wound-healing potato tuber system to explore global transcriptome changes during the early stages of wound-healing. Wounding leads to initial and substantial transcriptional changes that follow distinctive temporal patterns - primary metabolic pathways were already functional, or up-regulated immediately, and maintained at levels that would allow for precursor carbon skeletons and energy to feed into downstream metabolic processes. Genes involved in pathways for phenolic production (i.e., the shikimate pathway and phenylpropanoid metabolism) were up-regulated early while those involved in aliphatic suberin production (i.e., fatty acid biosynthesis and modification) were transcribed later into the time course. The pattern of accumulation of genes associated with ABA biosynthesis and degradation steps support a role for ABA in regulating aliphatic suberin production. Evaluation of putative Casparian strip membrane-like genes pinpointed wound-responsive candidates that may mediate the suberin deposition process.


Subject(s)
Solanum tuberosum , Solanum tuberosum/genetics , Solanum tuberosum/metabolism , Transcriptome , Lipids , Plant Tubers/genetics , Plant Tubers/metabolism , Phenols/metabolism , Gene Expression Regulation, Plant
5.
Sci Rep ; 12(1): 14791, 2022 08 30.
Article in English | MEDLINE | ID: mdl-36042376

ABSTRACT

Environmental RNAi has been developed as a tool for reverse genetics studies and is an emerging pest control strategy. The ability of environmental RNAi to efficiently down-regulate the expression of endogenous gene targets assumes efficient uptake of dsRNA and its processing. In addition, its efficiency can be augmented by the systemic spread of RNAi signals. Environmental RNAi is now a well-established tool for the manipulation of gene expression in the chelicerate acari, including the two-spotted spider mite, Tetranychus urticae. Here, we focused on eight single and ubiquitously-expressed genes encoding proteins with essential cellular functions. Application of dsRNAs that specifically target these genes led to whole mite body phenotypes-dark or spotless. These phenotypes were associated with a significant reduction of target gene expression, ranging from 20 to 50%, when assessed at the whole mite level. Histological analysis of mites treated with orally-delivered dsRNAs was used to investigate the spatial range of the effectiveness of environmental RNAi. Although macroscopic changes led to two groups of body phenotypes, silencing of target genes was associated with the distinct cellular phenotypes. We show that regardless of the target gene tested, cells that displayed histological changes were those that are in direct contact with the dsRNA-containing gut lumen, suggesting that the greatest efficiency of the orally-delivered dsRNAs is localized to gut tissues in T. urticae.


Subject(s)
Tetranychidae , Animals , Pest Control , RNA Interference , RNA, Double-Stranded/genetics , Tetranychidae/genetics
6.
Plant Physiol ; 189(4): 1961-1975, 2022 08 01.
Article in English | MEDLINE | ID: mdl-35348790

ABSTRACT

Glucosinolates are antiherbivory chemical defense compounds in Arabidopsis (Arabidopsis thaliana). Specialist herbivores that feed on brassicaceous plants have evolved various mechanisms aimed at preventing the formation of toxic isothiocyanates. In contrast, generalist herbivores typically detoxify isothiocyanates through glutathione conjugation upon exposure. Here, we examined the response of an extreme generalist herbivore, the two-spotted spider mite Tetranychus urticae (Koch), to indole glucosinolates. Tetranychus urticae is a composite generalist whose individual populations have a restricted host range but have an ability to rapidly adapt to initially unfavorable plant hosts. Through comparative transcriptomic analysis of mite populations that have differential susceptibilities to Arabidopsis defenses, we identified ß-cyanoalanine synthase of T. urticae (TuCAS), which encodes an enzyme with dual cysteine and ß-cyanoalanine synthase activities. We combined Arabidopsis genetics, chemical complementation and mite reverse genetics to show that TuCAS is required for mite adaptation to Arabidopsis through its ß-cyanoalanine synthase activity. Consistent with the ß-cyanoalanine synthase role in detoxification of hydrogen cyanide (HCN), we discovered that upon mite herbivory, Arabidopsis plants release HCN. We further demonstrated that indole glucosinolates are sufficient for cyanide formation. Overall, our study uncovered Arabidopsis defenses that rely on indole glucosinolate-dependent cyanide for protection against mite herbivory. In response, Arabidopsis-adapted mites utilize the ß-cyanoalanine synthase activity of TuCAS to counter cyanide toxicity, highlighting the mite's ability to activate resistant traits that enable this extreme polyphagous herbivore to exploit cyanogenic host plants.


Subject(s)
Arabidopsis , Tetranychidae , Animals , Arabidopsis/genetics , Cyanides , Glucosinolates , Herbivory , Indoles , Isothiocyanates , Lyases , Plants , Tetranychidae/physiology
7.
Plant Physiol ; 187(4): 2608-2622, 2021 12 04.
Article in English | MEDLINE | ID: mdl-34618096

ABSTRACT

Genetic adaptation, occurring over a long evolutionary time, enables host-specialized herbivores to develop novel resistance traits and to efficiently counteract the defenses of a narrow range of host plants. In contrast, physiological acclimation, leading to the suppression and/or detoxification of host defenses, is hypothesized to enable broad generalists to shift between plant hosts. However, the host adaptation mechanisms used by generalists composed of host-adapted populations are not known. Two-spotted spider mite (TSSM; Tetranychus urticae) is an extreme generalist herbivore whose individual populations perform well only on a subset of potential hosts. We combined experimental evolution, Arabidopsis thaliana genetics, mite reverse genetics, and pharmacological approaches to examine mite host adaptation upon the shift of a bean (Phaseolus vulgaris)-adapted population to Arabidopsis. We showed that cytochrome P450 monooxygenases are required for mite adaptation to Arabidopsis. We identified activities of two tiers of P450s: general xenobiotic-responsive P450s that have a limited contribution to mite adaptation to Arabidopsis and adaptation-associated P450s that efficiently counteract Arabidopsis defenses. In approximately 25 generations of mite selection on Arabidopsis plants, mites evolved highly efficient detoxification-based adaptation, characteristic of specialist herbivores. This demonstrates that specialization to plant resistance traits can occur within the ecological timescale, enabling the TSSM to shift to novel plant hosts.


Subject(s)
Adaptation, Biological , Arabidopsis/physiology , Arthropod Proteins/genetics , Cytochrome P-450 Enzyme System/genetics , Herbivory , Phaseolus/physiology , Tetranychidae/physiology , Animals , Arthropod Proteins/metabolism , Food Chain , Tetranychidae/genetics
8.
Plant Physiol ; 187(1): 116-132, 2021 09 04.
Article in English | MEDLINE | ID: mdl-34618148

ABSTRACT

Arabidopsis (Arabidopsis thaliana) defenses against herbivores are regulated by the jasmonate (JA) hormonal signaling pathway, which leads to the production of a plethora of defense compounds. Arabidopsis defense compounds include tryptophan-derived metabolites, which limit Arabidopsis infestation by the generalist herbivore two-spotted spider mite, Tetranychus urticae. However, the phytochemicals responsible for Arabidopsis protection against T. urticae are unknown. Here, we used Arabidopsis mutants disrupted in the synthesis of tryptophan-derived secondary metabolites to identify phytochemicals involved in the defense against T. urticae. We show that of the three tryptophan-dependent pathways found in Arabidopsis, the indole glucosinolate (IG) pathway is necessary and sufficient to assure tryptophan-mediated defense against T. urticae. We demonstrate that all three IGs can limit T. urticae herbivory, but that they must be processed by myrosinases to hinder T. urticae oviposition. Putative IG breakdown products were detected in mite-infested leaves, suggesting in planta processing by myrosinases. Finally, we demonstrate that besides IGs, there are additional JA-regulated defenses that control T. urticae herbivory. Together, our results reveal the complexity of Arabidopsis defenses against T. urticae that rely on multiple IGs, specific myrosinases, and additional JA-dependent defenses.


Subject(s)
Arabidopsis/physiology , Glucosinolates/metabolism , Glycoside Hydrolases/metabolism , Herbivory , Indoles/metabolism , Plant Defense Against Herbivory , Plant Proteins/metabolism , Animals , Arabidopsis/enzymology , Tetranychidae/physiology
9.
Sci Rep ; 10(1): 19126, 2020 11 05.
Article in English | MEDLINE | ID: mdl-33154461

ABSTRACT

Comprehensive understanding of pleiotropic roles of RNAi machinery highlighted the conserved chromosomal functions of RNA interference. The consequences of the evolutionary variation in the core RNAi pathway genes are mostly unknown, but may lead to the species-specific functions associated with gene silencing. The two-spotted spider mite, Tetranychus urticae, is a major polyphagous chelicerate pest capable of feeding on over 1100 plant species and developing resistance to pesticides used for its control. A well annotated genome, susceptibility to RNAi and economic importance, make T. urticae an excellent candidate for development of an RNAi protocol that enables high-throughput genetic screens and RNAi-based pest control. Here, we show that the length of the exogenous dsRNA critically determines its processivity and ability to induce RNAi in vivo. A combination of the long dsRNAs and the use of dye to trace the ingestion of dsRNA enabled the identification of genes involved in membrane transport and 26S proteasome degradation as sensitive RNAi targets. Our data demonstrate that environmental RNAi can be an efficient reverse genetics and pest control tool in T. urticae. In addition, the species-specific properties together with the variation in the components of the RNAi machinery make T. urticae a potent experimental system to study the evolution of RNAi pathways.


Subject(s)
RNA Interference , RNA, Double-Stranded , Tetranychidae/genetics , Animals , Biological Transport/genetics , Gene Silencing , Proteasome Endopeptidase Complex/genetics
10.
Sci Rep ; 10(1): 18471, 2020 10 28.
Article in English | MEDLINE | ID: mdl-33116211

ABSTRACT

Spider mites constitute an assemblage of well-known pests in agriculture, but are less known for their ability to spin silk of nanoscale diameters and high Young's moduli. Here, we characterize silk of the gorse spider mite Tetranychus lintearius, which produces copious amounts of silk with nano-dimensions. We determined biophysical characteristics of the silk fibres and manufactured nanoparticles and biofilm derived from native silk. We determined silk structure using attenuated total reflectance Fourier transform infrared spectroscopy, and characterized silk nanoparticles using field emission scanning electron microscopy. Comparative studies using T. lintearius and silkworm silk nanoparticles and biofilm demonstrated that spider mite silk supports mammalian cell growth in vitro and that fluorescently labelled nanoparticles can enter cell cytoplasm. The potential for cytocompatibility demonstrated by this study, together with the prospect of recombinant silk production, opens a new avenue for biomedical application of this little-known silk.


Subject(s)
Biocompatible Materials , Materials Testing , Nanoparticles/chemistry , Silk/chemistry , Tetranychidae/chemistry , Animals , Biocompatible Materials/chemistry , Biocompatible Materials/pharmacokinetics , Biocompatible Materials/pharmacology , Cell Line , Elastic Modulus , Mice , Microscopy, Electron, Scanning , Nanoparticles/ultrastructure
11.
Pestic Biochem Physiol ; 170: 104677, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32980052

ABSTRACT

Two-spotted spider mite (TSSM) Tetranychus urticae (Koch) is an important agricultural pest that causes considerable yield losses to over 150 field and greenhouse crops. Mitochondrial electron transport inhibitors (METI) acaricides are commonly used to control mite species in commercial Canadian greenhouses. Development of resistance to METIs in TSSM populations have been reported worldwide, but not until recently in Canada. The objectives of this study were to: 1) monitor the acaricide-susceptibility in greenhouse TSSM populations, and 2) investigate the resistance to pyridaben, a METI acaricide, in greenhouse resistant and pyridaben-selected (SRS) mite strains. The increased mortality to the pyridaben sub-lethal concentration (LC30) when SRS mites were exposed to piperonyl butoxide (PBO), a general cytochrome P450 monooxygenase inhibitor, and higher P450 activity compared to the greenhouse strain (RS) mites, indicated that P450s may be at least partially responsible for the resistance. The molecular mechanisms of target site insensitivity-mediated resistance in the pyridaben resistant strain of TSSM were investigated by comparing the DNA sequence of NADH dehydrogenase subunits TYKY and PSST, NADH-ubiquinone oxidoreductase chain 1 and 5 (ND1, ND5) and the NADH-ubiquinone oxidoreductase subunit 49 kDa from SRS to the reference strain (SS) and RS. Despite a number of nucleotide substitutions, none correlated with the pyridaben resistance. Understanding the underlying mechanisms of TSSM adaptation to acaricides is an essential part of resistance management strategy in any IPM program. The findings of this study will encourage growers to apply acaricides with different modes of action to reduce the rate at which acaricide resistance will occur in greenhouse TSSM populations.


Subject(s)
Acaricides/pharmacology , Mites/drug effects , Tetranychidae/drug effects , Animals , Canada , Drug Resistance , Pyridazines
12.
IUCrJ ; 6(Pt 5): 895-908, 2019 Sep 01.
Article in English | MEDLINE | ID: mdl-31576222

ABSTRACT

The data quality requirements for charge density studies on actinide compounds are extreme. Important steps in data collection and reduction required to obtain such data are summarized and evaluated. The steps involved in building an augmented Hansen-Coppens multipole model for an actinide pseudo-atom are provided. The number and choice of radial functions, in particular the definition of the core, valence and pseudo-valence terms are discussed. The conclusions in this paper are based on a re-examination and improvement of a previously reported study on [PPh4][UF6]. Topological analysis of the total electron density shows remarkable agreement between experiment and theory; however, there are significant differences in the Laplacian distribution close to the uranium atoms which may be due to the effective core potential employed for the theoretical calculations.

13.
IUCrJ ; 6(Pt 1): 56-65, 2019 Jan 01.
Article in English | MEDLINE | ID: mdl-30713703

ABSTRACT

Chemical bonding and all intermolecular interactions in the highly insoluble carbonate salt of a 2,6-pyridine-bis(iminoguanidine), (PyBIGH2)(CO3)(H2O)4, recently employed in the direct air capture of CO2 via crystallization, have been analyzed within the framework of the quantum theory of atoms in molecules (QTAIM) based on the experimental electron density derived from X-ray diffraction data obtained at 20 K. Accurate hydrogen positions were included based on an analogous neutron diffraction study at 100 K. Topological features of the covalent bonds demonstrate the presence of multiple bonds of various orders within the PyBIGH2 2+ cation. Strong hydrogen bonds define ribbons comprising carbonate anions and water molecules. These ribbons are linked to stacks of essentially planar dications via hydrogen bonds from the guanidinium moieties and an additional one to the pyridine nitro-gen. The linking hydrogen bonds are approximately perpendicular to the anion-water ribbons. The observation of these putative interactions provided motivation to characterize them by topological analysis of the total electron density. Thus, all hydrogen bonds have been characterized by the properties of their (3,-1) bond critical points. Weaker interactions between the PyBIGH2 2+ cations have similarly been characterized. Integrated atomic charges are also reported. A small amount of cocrystallized hydroxide ion (∼2%) was also detected in both the X-ray and neutron data, and included in the multipole model for the electron-density refinement. The small amount of additional H+ required for charge balance was not detected in either the X-ray or the neutron data. The results are discussed in the context of the unusually low aqueous solubility of (PyBIGH2)(CO3)(H2O)4 and its ability to sequester atmospheric CO2.

14.
J Phys Chem A ; 122(50): 9676-9687, 2018 Dec 20.
Article in English | MEDLINE | ID: mdl-30457862

ABSTRACT

Accurate experimental determination of the electron density distribution for the energetic ionic salt bis(ammonium) 2,2'-dinitramido-5,5'-bis(1-oxa-3,4-diazolate) dihydrate (1) is obtained from multipole modeling of single-crystal X-ray diffraction data collected at 20 K. The intra- and intermolecular bonding is assessed in terms of the quantum theory of atoms in molecules (QTAIM) with a view to better understanding the physicochemical properties in relation to chemical bonding. Topological analysis reveals stronger bonding for the N-NO2 bond relative to energetic nitramines RDX and HMX and the indication of a trend between this and impact sensitivity of nitro-containing energetic materials is noted. The intermolecular bonding of 1 is dominated by classical H-bonds but includes multiple π-bonding interactions and interactions between H-bond donor and acceptor atoms where bond paths are deflected by H atoms. There also exists a weak O···O interaction between end-on nitro groups, as well as an intramolecular ring-forming 1,5-type interaction. An anharmonic description of thermal motion was required to obtain the best fitting model, despite the low temperature of the study. The experimental study was complemented by periodic boundary DFT calculations at the experimental geometry as well as gas phase calculations on the isolated dianion.

15.
Front Plant Sci ; 9: 1206, 2018.
Article in English | MEDLINE | ID: mdl-30271412

ABSTRACT

The two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most polyphagous herbivores, feeding on more than 1,100 plant species. Its wide host range suggests that TSSM has an extraordinary ability to modulate its digestive and xenobiotic physiology. The analysis of the TSSM genome revealed the expansion of gene families that encode proteins involved in digestion and detoxification, many of which were associated with mite responses to host shifts. The majority of plant defense compounds that directly impact mite fitness are ingested. They interface mite compounds aimed at counteracting their effect in the gut. Despite several detailed ultrastructural studies, our knowledge of the TSSM digestive tract that is needed to support the functional analysis of digestive and detoxification physiology is lacking. Here, using a variety of histological and microscopy techniques, and a diversity of tracer dyes, we describe the organization and properties of the TSSM alimentary system. We define the cellular nature of floating vesicles in the midgut lumen that are proposed to be the site of intracellular digestion of plant macromolecules. In addition, by following the TSSM's ability to intake compounds of defined sizes, we determine a cut off size for the ingestible particles. Moreover, we demonstrate the existence of a distinct filtering function between midgut compartments which enables separation of molecules by size. Furthermore, we broadly define the spatial distribution of the expression domains of genes involved in digestion and detoxification. Finally, we discuss the relative simplicity of the spider mite digestive system in the context of mite's digestive and xenobiotic physiology, and consequences it has on the effectiveness of plant defenses.

17.
J Phys Chem A ; 121(46): 8962-8972, 2017 Nov 22.
Article in English | MEDLINE | ID: mdl-29087718

ABSTRACT

The intra- and intermolecular bonding in the known phase of dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate, TKX-50, has been analyzed on the basis of the experimentally determined charge density distribution from high-resolution X-ray diffraction data obtained at 20 K. This was compared to the charge density obtained from DFT calculations with periodic boundary conditions using both direct calculations and derived structure factors. Results of topological analysis of the electron density corroborate that TKX-50 is best described as a layered structure linked primarily by a number of hydrogen bonds as well as by a variety of other interactions. Additional bonding interactions were identified, including a pair of equivalent 1,5-type intramolecular closed-shell interactions in the dianion. Refinement of anharmonic motion was shown to be essential for obtaining an adequate model, despite the low temperature of the study. Although generally unusual, the implementation of anharmonic refinement provided a significant improvement compared to harmonic refinement of both traditional and split-core multipole models.

18.
Mol Plant Microbe Interact ; 30(12): 935-945, 2017 12.
Article in English | MEDLINE | ID: mdl-28857675

ABSTRACT

Plant-herbivore interactions evolved over long periods of time, resulting in an elaborate arms race between interacting species. While specialist herbivores evolved specific strategies to cope with the defenses of a limited number of hosts, our understanding of how generalist herbivores deal with the defenses of a plethora of diverse host plants is largely unknown. Understanding the interaction between a plant host and a generalist herbivore requires an understanding of the plant's mechanisms aimed at defending itself and the herbivore's mechanisms intended to counteract diverse defenses. In this review, we use the two-spotted spider mite (TSSM), Tetranychus urticae (Koch) as an example of a generalist herbivore, as this chelicerate pest has a staggering number of plant hosts. We first establish that the ability of TSSM to adapt to marginal hosts underlies its polyphagy and agricultural pest status. We then highlight our understanding of direct plant defenses against spider mite herbivory and review recent advances in uncovering mechanisms of spider mite adaptations to them. Finally, we discuss the adaptation process itself, as it allows TSSM to overcome initially effective plant defenses. A high-quality genome sequence and developing genetic tools, coupled with an ease of mite experimental selection to new hosts, make TSSM an outstanding system to study the evolution of host range, mechanisms of pest xenobiotic resistance and plant-herbivore interactions. In addition, knowledge of plant defense mechanisms that affect mite fitness are of practical importance, as it can lead to development of new control strategies against this important agricultural pest. In parallel, understanding mechanisms of mite counter adaptations to these defenses is required to maintain the efficacy of these control strategies in agricultural practices.


Subject(s)
Herbivory , Plants/parasitology , Tetranychidae/physiology , Adaptation, Physiological , Animals , Host-Pathogen Interactions , Tetranychidae/ultrastructure
19.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 73(Pt 4): 654-659, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28762975

ABSTRACT

A high-resolution X-ray diffraction measurement of 2,5-dichloro-1,4-benzoquinone (DCBQ) at 20 K was carried out. The experimental charge density was modeled using the Hansen-Coppens multipolar expansion and the topology of the electron density was analyzed in terms of the quantum theory of atoms in molecules (QTAIM). Two different multipole models, predominantly differentiated by the treatment of the chlorine atom, were obtained. The experimental results have been compared to theoretical results in the form of a multipolar refinement against theoretical structure factors and through direct topological analysis of the electron density obtained from the optimized periodic wavefunction. The similarity of the properties of the total electron density in all cases demonstrates the robustness of the Hansen-Coppens formalism. All intra- and intermolecular interactions have been characterized.

20.
PLoS One ; 12(7): e0180658, 2017.
Article in English | MEDLINE | ID: mdl-28686745

ABSTRACT

The two-spotted spider mite, Tetranychus urticae, is a chelicerate herbivore with an extremely wide host range and an extraordinary ability to develop pesticide resistance. Due to its responsiveness to natural and synthetic xenobiotics, the spider mite is becoming a prime pest herbivore model for studies of the evolution of host range, plant-herbivore interactions and mechanisms of xenobiotic resistance. The spider mite genome has been sequenced and its transcriptional responses to developmental and various biotic and abiotic cues have been documented. However, to identify biological and evolutionary roles of T. urticae genes and proteins, it is necessary to develop methods for the efficient manipulation of mite gene function or protein activity. Here, we describe protocols developed for the delivery of small molecules into spider mites. Starting with mite maintenance and the preparation of the experimental mite populations of developmentally synchronized larvae and adults, we describe 3 methods for delivery of small molecules including artificial diet, leaf coating, and soaking. The presented results define critical steps in these methods and demonstrate that they can successfully deliver tracer dyes into mites. Described protocols provide guidelines for high-throughput setups for delivery of experimental compounds that could be used in reverse genetics platforms to modulate gene expression or protein activity, or for screens focused on discovery of new molecules for mite control. In addition, described protocols could be adapted for other Tetranychidae and related species of economic importance such as Varroa, dust and poultry mites.


Subject(s)
Drug Delivery Systems , Pesticides/pharmacology , Phylogeny , Tetranychidae/drug effects , Animals , Drug Resistance/genetics , Herbivory/drug effects , Host Specificity , Host-Parasite Interactions/drug effects , Pesticides/chemistry , Plants/parasitology , Tetranychidae/pathogenicity
SELECTION OF CITATIONS
SEARCH DETAIL
...