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1.
Parasitology ; 151(1): 102-107, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38018393

RESUMO

Hookworm infection affects millions globally, leading to chronic conditions like malnutrition and anaemia. Among the hookworm species, Ancylostoma ceylanicum stands out as a generalist, capable of infecting various hosts, including humans, cats, dogs and hamsters. Surprisingly, it cannot establish in mice, despite their close phylogenetic relationship to hamsters. The present study investigated the development of A. ceylanicum in immunodeficient NSG mice to determine the contribution of the immune system to host restriction. The infections became patent on day 19 post-infection (PI) and exhibited elevated egg production which lasted for at least 160 days PI. Infective A. ceylanicum larvae reared from eggs released by infected NSG mice were infectious to hamsters and capable of reproduction, indicating that the adults in the NSG mice were producing viable offspring. In contrast, A. ceylanicum showed limited development in outbred Swiss Webster mice. Furthermore, the closely related canine hookworm Ancylostoma caninum was unable to infect and develop in NSG mice, indicating that different mechanisms may determine host specificity even in closely related species. This is the first report of any hookworm species completing its life cycle in a mouse and implicate the immune system in determining host specificity in A. ceylanicum.


Assuntos
Ancylostoma , Infecções por Uncinaria , Humanos , Cricetinae , Adulto , Animais , Cães , Camundongos , Ancylostomatoidea , Filogenia , Infecções por Uncinaria/veterinária , Especificidade de Hospedeiro
2.
Parasitology ; 151(3): 271-281, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38163962

RESUMO

Parasitic gastrointestinal nematodes pose significant health risks to humans, livestock, and companion animals, and their control relies heavily on the use of anthelmintic drugs. Overuse of these drugs has led to the emergence of resistant nematode populations. Herein, a naturally occurring isolate (referred to as BCR) of the dog hookworm, Ancylostoma caninum, that is resistant to 3 major classes of anthelmintics is characterized. Various drug assays were used to determine the resistance of BCR to thiabendazole, ivermectin, moxidectin and pyrantel pamoate. When compared to a drug-susceptible isolate of A. caninum, BCR was shown to be significantly resistant to all 4 of the drugs tested. Multiple single nucleotide polymorphisms have been shown to impart benzimidazole resistance, including the F167Y mutation in the ß-tubulin isotype 1 gene, which was confirmed to be present in BCR through molecular analysis. The frequency of the resistant allele in BCR was 76.3% following its first passage in the lab, which represented an increase from approximately 50% in the founding hookworm population. A second, recently described mutation in codon 134 (Q134H) was also detected at lower frequency in the BCR population. Additionally, BCR exhibits an altered larval activation phenotype compared to the susceptible isolate, suggesting differences in the signalling pathways involved in the activation process which may be associated with resistance. Further characterization of this isolate will provide insights into the mechanisms of resistance to macrocyclic lactones and tetrahydropyrimidine anthelmintics.


Assuntos
Ancylostoma , Anti-Helmínticos , Humanos , Cães , Animais , Ancylostoma/genética , Ancylostomatoidea , Larva/genética , Anti-Helmínticos/farmacologia , Resistência a Múltiplos Medicamentos/genética , Resistência a Medicamentos/genética
3.
Parasitology ; 150(6): 511-523, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36883013

RESUMO

Soil-transmitted nematodes (STNs) place a tremendous burden on health and economics worldwide with an estimate of at least 1.5 billion people, or 24% of the population, being infected with at least 1 STN globally. Children and pregnant women carry the heavier pathological burden, and disease caused by the blood-feeding worm in the intestine can result in anaemia and delays in physical and intellectual development. These parasites are capable of infecting and reproducing in various host species, but what determines host specificity remains unanswered. Identifying the molecular determinants of host specificity would provide a crucial breakthrough towards understanding the biology of parasitism and could provide attractive targets for intervention. To investigate specificity mechanisms, members of the hookworm genus Ancylostoma provide a powerful system as they range from strict specialists to generalists. Using transcriptomics, differentially expressed genes (DEGs) in permissive (hamster) and non-permissive (mouse) hosts at different early time points during infection with A. ceylanicum were examined. Analysis of the data has identified unique immune responses in mice, as well as potential permissive signals in hamsters. Specifically, immune pathways associated with resistance to infection are upregulated in the non-permissive host, providing a possible protection mechanism that is absent in the permissive host. Furthermore, unique signatures of host specificity that may inform the parasite that it has invaded a permissive host were identified. These data provide novel insight into the tissue-specific gene expression differences between permissive and non-permissive hosts in response to hookworm infection.


Assuntos
Ancilostomíase , Infecções por Uncinaria , Gravidez , Cricetinae , Feminino , Animais , Humanos , Camundongos , Ancylostoma/genética , Ancilostomíase/parasitologia , Especificidade de Hospedeiro , Transcriptoma , Intestinos
4.
J Biol Chem ; 292(13): 5364-5377, 2017 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-28196860

RESUMO

NCLX is a Na+/Ca2+ exchanger that uses energy stored in the transmembrane sodium gradient to facilitate the exchange of sodium ions for ionic calcium. Mammals have a single NCLX, which has been shown to function primarily at the mitochondrion and is an important regulator of neuronal physiology by contributing to neurotransmission and synaptic plasticity. The role of NCLX in developmental cell patterning (e.g. in neural circuits) is largely unknown. Here we describe a novel role for the Caenorhabditis elegans NCLX-type protein, NCX-9, in neural circuit formation. NCX-9 functions in hypodermal seam cells that secrete the axon guidance cue UNC-129/BMP, and our data revealed that ncx-9-/- mutant animals exhibit development defects in stereotyped left/right axon guidance choices within the GABAergic motor neuron circuit. Our data also implicate NCX-9 in a LON-2/heparan sulfate and UNC-6/netrin-mediated, RAC-dependent signaling pathway to guide left/right patterning within this circuit. Finally, we also provide in vitro physiology data supporting the role for NCX-9 in handling calcium exchange at the mitochondrion. Taken together, our work reveals the specificity by which the handling by NCLX of calcium exchange can map to neural circuit patterning and axon guidance decisions during development.


Assuntos
Orientação de Axônios/fisiologia , Padronização Corporal/fisiologia , Caenorhabditis elegans/fisiologia , Trocador de Sódio e Cálcio/fisiologia , Animais , Caenorhabditis elegans/crescimento & desenvolvimento , Proteínas de Caenorhabditis elegans/fisiologia , Cálcio/metabolismo , Mitocôndrias/metabolismo , Transdução de Sinais , Fator de Crescimento Transformador beta/fisiologia
5.
BMC Neurosci ; 19(1): 19, 2018 04 13.
Artigo em Inglês | MEDLINE | ID: mdl-29649983

RESUMO

Na+/Ca2+ exchangers are low-affinity high-capacity transporters that mediate Ca2+ extrusion by coupling Ca2+ efflux to the influx of Na+ ions. The Na+/Ca2+ exchangers form a super-family comprised of three branches each differing in ion-substrate selectivity: Na+/Ca2+ exchangers (NCX), Na+/Ca2+/K+ exchangers, and Ca2+/cation exchangers. Their primary function is to maintain Ca2+ homeostasis and play a particularly important role in excitable cells that experience transient Ca2+ fluxes. Research into the role and activity of Na+/Ca2+ exchangers has focused extensively on the cardio-vascular system, however, growing evidence suggests that Na+/Ca2+ exchangers play a key role in neuronal processes such as memory formation, learning, oligodendrocyte differentiation, neuroprotection during brain ischemia and axon guidance. They have also been implicated in pathologies such as Alzheimer's disease, Parkinson's disease, Multiple Sclerosis and Epilepsy, however, a clear understanding of their mechanism during disease is lacking. To date, there has never been a central resource or database for Na+/Ca2+ exchangers. With clear disease relevance and ever-increasing research on Na+/Ca2+ exchangers from both model and non-model species, a database that unifies the data on Na+/Ca2+ exchangers is needed for future research. NCX-DB is a publicly available database with a web interface that enables users to explore various Na+/Ca2+ exchangers, perform cross-species sequence comparison, identify new exchangers, and stay-up to date with recent literature. NCX-DB is available on the web via an interactive user interface with an intuitive design, which is applicable for the identification and comparison of Na+/Ca2+ exchanger proteins across diverse species.


Assuntos
Cálcio/metabolismo , Homeostase/fisiologia , Memória/fisiologia , Trocador de Sódio e Cálcio/metabolismo , Animais , Encefalopatias/metabolismo , Bases de Dados como Assunto
6.
J Cell Sci ; 126(Pt 19): 4381-95, 2013 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23886944

RESUMO

Primary cilia are ubiquitous sensory organelles that concentrate transmembrane signaling proteins essential for sensing environmental cues. Mislocalization of crucial ciliary signaling proteins, such as the tetrameric cyclic nucleotide-gated (CNG) channels, can lead to cellular dysfunction and disease. Although several cis- and trans-acting factors required for ciliary protein trafficking and localization have been identified, whether these mechanisms act in a protein- and cell-specific manner is largely unknown. Here, we show that CNG channel subunits can be localized to discrete ciliary compartments in individual sensory neurons in C. elegans, suggesting that channel composition is heterogeneous across the cilium. We demonstrate that ciliary localization of CNG channel subunits is interdependent on different channel subunits in specific cells, and identify sequences required for efficient ciliary targeting and localization of the TAX-2 CNGB and TAX-4 CNGA subunits. Using a candidate gene approach, we show that Inversin, transition zone proteins, intraflagellar transport motors and a MYND-domain protein are required to traffic and/or localize CNG channel subunits in both a cell- and channel subunit-specific manner. We further find that TAX-2 and TAX-4 are relatively immobile in specific sensory cilia subcompartments, suggesting that these proteins undergo minimal turnover in these domains in mature cilia. Our results uncover unexpected diversity in the mechanisms that traffic and localize CNG channel subunits to cilia both within and across cell types, highlighting the essential contribution of this process to cellular functions.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Cílios/metabolismo , Canais de Cátion Regulados por Nucleotídeos Cíclicos/metabolismo , Animais , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Movimento Celular , Transdução de Sinais
7.
Genesis ; 52(2): 93-109, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24376088

RESUMO

Maintenance of calcium homeostasis is necessary for the development and survival of all animals. Calcium ions modulate excitability and bind effectors capable of initiating many processes such as muscular contraction and neurotransmission. However, excessive amounts of calcium in the cytosol or within intracellular calcium stores can trigger apoptotic pathways in cells that have been implicated in cardiac and neuronal pathologies. Accordingly, it is critical for cells to rapidly and effectively regulate calcium levels. The Na(+) /Ca(2+) exchangers (NCX), Na(+) /Ca(2+) /K(+) exchangers (NCKX), and Ca(2+) /Cation exchangers (CCX) are the three classes of sodium calcium antiporters found in animals. These exchanger proteins utilize an electrochemical gradient to extrude calcium. Although they have been studied for decades, much is still unknown about these proteins. In this review, we examine current knowledge about the structure, function, and physiology and also discuss their implication in various developmental disorders. Finally, we highlight recent data characterizing the family of sodium calcium exchangers in the model system, Caenorhabditis elegans, and propose that C. elegans may be an ideal model to complement other systems and help fill gaps in our knowledge of sodium calcium exchange biology.


Assuntos
Cálcio/metabolismo , Família Multigênica , Trocador de Sódio e Cálcio/química , Trocador de Sódio e Cálcio/metabolismo , Animais , Caenorhabditis elegans/química , Caenorhabditis elegans/metabolismo , Sinalização do Cálcio , Regulação da Expressão Gênica , Humanos , Mitocôndrias/metabolismo , Modelos Moleculares , Filogenia , Trocador de Sódio e Cálcio/genética
8.
Proc Natl Acad Sci U S A ; 107(13): 6016-21, 2010 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-20220099

RESUMO

To navigate a complex and changing environment, an animal's sensory neurons must continually adapt to persistent cues while remaining responsive to novel stimuli. Long-term exposure to an inherently attractive odor causes Caenorhabditis elegans to ignore that odor, a process termed odor adaptation. Odor adaptation is likely to begin within the sensory neuron, because it requires factors that act within these cells at the time of odor exposure. The process by which an olfactory sensory neuron makes a decisive shift over time from a receptive state to a lasting unresponsive one remains obscure. In C. elegans, adaptation to odors sensed by the AWC pair of olfactory neurons requires the cGMP-dependent protein kinase EGL-4. Using a fully functional, GFP-tagged EGL-4, we show here that prolonged odor exposure sends EGL-4 into the nucleus of the stimulated AWC neuron. This odor-induced nuclear translocation correlates temporally with the stable dampening of chemotaxis that is indicative of long-term adaptation. Long-term adaptation requires cGMP binding residues as well as an active EGL-4 kinase. We show here that EGL-4 nuclear accumulation is both necessary and sufficient to induce long-lasting odor adaptation. After it is in the AWC nucleus, EGL-4 decreases the animal's responsiveness to AWC-sensed odors by acting downstream of the primary sensory transduction. Thus, the EGL-4 protein kinase acts as a sensor that integrates odor signaling over time, and its nuclear translocation is an instructive switch that allows the animal to ignore persistent odors.


Assuntos
Proteínas de Caenorhabditis elegans/fisiologia , Caenorhabditis elegans/fisiologia , Proteínas Quinases Dependentes de GMP Cíclico/fisiologia , Olfato/fisiologia , Transporte Ativo do Núcleo Celular , Adaptação Fisiológica , Animais , Animais Geneticamente Modificados , Comportamento Animal/fisiologia , Sítios de Ligação , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , GMP Cíclico/metabolismo , Proteínas Quinases Dependentes de GMP Cíclico/química , Proteínas Quinases Dependentes de GMP Cíclico/genética , Expressão Gênica , Genes de Helmintos , Modelos Neurológicos , Odorantes , Neurônios Receptores Olfatórios/fisiologia , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Transdução de Sinais
9.
PLoS Genet ; 5(12): e1000761, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20011101

RESUMO

While most sensory neurons will adapt to prolonged stimulation by down-regulating their responsiveness to the signal, it is not clear which events initiate long-lasting sensory adaptation. Likewise, we are just beginning to understand how the physiology of the adapted cell is altered. Caenorhabditis elegans is inherently attracted to specific odors that are sensed by the paired AWC olfactory sensory neurons. The attraction diminishes if the animal experiences these odors for a prolonged period of time in the absence of food. The AWC neuron responds acutely to odor-exposure by closing calcium channels. While odortaxis requires a Galpha subunit protein, cGMP-gated channels, and guanylyl cyclases, adaptation to prolonged odor exposure requires nuclear entry of the cGMP-dependent protein kinase, EGL-4. We asked which candidate members of the olfactory signal transduction pathway promote nuclear entry of EGL-4 and which molecules might induce long-term adaptation downstream of EGL-4 nuclear entry. We found that initiation of long-term adaptation, as assessed by nuclear entry of EGL-4, is dependent on G-protein mediated signaling but is independent of fluxes in calcium levels. We show that long-term adaptation requires polyunsaturated fatty acids (PUFAs) that may act on the transient receptor potential (TRP) channel type V OSM-9 downstream of EGL-4 nuclear entry. We also present evidence that high diacylglycerol (DAG) levels block long-term adaptation without affecting EGL-4 nuclear entry. Our analysis provides a model for the process of long-term adaptation that occurs within the AWC neuron of C. elegans: G-protein signaling initiates long-lasting olfactory adaptation by promoting the nuclear entry of EGL-4, and once EGL-4 has entered the nucleus, processes such as PUFA activation of the TRP channel OSM-9 may dampen the output of the AWC neuron.


Assuntos
Caenorhabditis elegans/fisiologia , Olfato/fisiologia , Adaptação Fisiológica , Animais , Proteínas de Caenorhabditis elegans/fisiologia , Sinalização do Cálcio , Núcleo Celular/metabolismo , GMP Cíclico/fisiologia , Proteínas Quinases Dependentes de GMP Cíclico/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Neurônios/fisiologia , Odorantes , Canais de Cátion TRPV/fisiologia
10.
G3 (Bethesda) ; 12(2)2022 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-35100348

RESUMO

Glutamate-gated chloride channels belong to the Cys-loop receptor superfamily. Glutamate-gated chloride channels are activated by glutamate and form substrates for the antiparasitic drugs from the avermectin family. Glutamate-gated chloride channels are pentameric, and each subunit contains an N-terminal extracellular domain that binds glutamate and 4 helical transmembrane domains, which contain binding sites for avermectin drugs. In order to provide more insight into phylum-wide patterns of glutamate-gated chloride subunit gene expansion and sequence diversity across nematodes, we have developed a database of predicted glutamate-gated chloride subunit genes from 125 nematode species. Our analysis into this dataset described assorted patterns of species-specific glutamate-gated chloride gene counts across different nematodes as well as sequence diversity in key residues thought to be involved in avermectin binding.


Assuntos
Cloretos , Ácido Glutâmico , Animais , Caenorhabditis elegans/genética , Canais de Cloreto/genética , Canais de Cloreto/metabolismo , Ácido Glutâmico/metabolismo
11.
Gene ; 810: 146052, 2022 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-34756961

RESUMO

Calcium signaling is ubiquitous in nematode development from fertilization to cell specification to apoptosis. Calcium also regulates dauer entry in Caenorhabditis elegans, which corresponds to the infective stage of parasitic nematodes. In diverse parasites such as Trypanosoma cruzi and Toxoplasma gondii calcium has been shown to regulate host cell entry and egress, and perturbing calcium signaling represents a possible route to inhibit infection and parasitism in these species. Sodium calcium exchangers are considered the most important mechanism of calcium efflux, and our lab has previously characterized the sodium calcium exchanger gene family in C. elegans and studied the diversity of this family across a subset of specific nematode species. Here we build upon these data and explore sodium calcium exchangers across 108 species of nematodes. Our data reveal substantial differences in sodium calcium exchanger counts across the Phylum and detail expansions and contractions of specific exchanger subtypes within certain nematode clades. Finally, we also provide evidence for a role of sodium calcium exchangers in parasite activation by examining differentially expressed genes in non-activated versus activated infective stage larvae. Taken together our findings paint a heterogeneous picture of sodium calcium exchanger evolution across the Phylum Nematoda that may reflect unique adaptations to free-living and parasitic lifestyles.


Assuntos
Proteínas de Helminto/genética , Nematoides/genética , Trocador de Sódio e Cálcio/genética , Motivos de Aminoácidos , Animais , Caenorhabditis elegans/genética , Sinalização do Cálcio , Evolução Molecular , Estudo de Associação Genômica Ampla , Humanos , Nematoides/classificação , Nematoides/fisiologia , Infecções por Nematoides/parasitologia , Trocador de Sódio e Cálcio/química
12.
J Vis Exp ; (181)2022 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-35435903

RESUMO

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema are obligate parasites of insects that live in the soil. The main characteristic of their life cycle is the mutualistic association with the bacteria Photorhabdus and Xenorhabdus, respectively. The nematode parasites are able to locate and enter suitable insect hosts, subvert the insect immune response, and multiply efficiently to produce the next generation that will actively hunt new insect prey to infect. Due to the properties of their life cycle, entomopathogenic nematodes are popular biological control agents, which are used in combination with insecticides to control destructive agricultural insect pests. Simultaneously, these parasitic nematodes represent a research tool to analyze nematode pathogenicity and host anti-nematode responses. This research is aided by the recent development of genetic techniques and transcriptomic approaches for understanding the role of nematode secreted molecules during infection. Here, a detailed protocol on maintaining entomopathogenic nematodes and using a gene knockdown procedure is provided. These methodologies further promote the functional characterization of entomopathogenic nematode infection factors.


Assuntos
Nematoides , Photorhabdus , Xenorhabdus , Animais , Insetos/genética , Nematoides/genética , Nematoides/microbiologia , Photorhabdus/genética , Simbiose/genética , Xenorhabdus/genética
13.
Biotechniques ; 71(3): 495-498, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34420406

RESUMO

Parasitic nematodes represent a significant threat to human health, causing diseases of major socioeconomic importance worldwide. Central to controlling infections of parasitic nematodes is a more detailed molecular picture of host specificity, parasite activation and immune suppression. CRISPR technology holds huge potential for researchers in the field of parasitic nematology, as it provides a powerful genetic tool to dissect questions in parasite biology. To expedite the development of CRISPR technology in parasitic nematodes, software is required to facilitate the design of effective and specific sgRNA sequences. Here, the author introduces CRISPR-PN2, a comprehensive web-based platform that provides flexible use control over the automated design of specific gRNA sequences for CRISPR experiments in parasitic nematodes.


Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Nematoides , Animais , Sistemas CRISPR-Cas , Edição de Genes , Nematoides/genética , RNA Guia de Cinetoplastídeos
14.
Parasitol Int ; 83: 102357, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33901678

RESUMO

It is estimated that one billion people globally are infected by parasitic nematodes, with children, pregnant women, and the elderly particularly susceptible to morbidity from infection. Control methods are limited to de-worming, which is hampered by rapid re-infection and the inevitable development of anthelmintic resistance. One family of proteins that has been implicated in nematode anthelmintic resistance are the ATP binding cassette (ABC) transporters. ABC transporters are characterized by a highly conserved ATP-binding domain and variable transmembrane regions. A growing number of studies have associated ABC transporters in anthelmintic resistance through a protective mechanism of drug efflux. Genetic deletion of P glycoprotein type ABC transporters in Caenorhabditis elegans demonstrated increased sensitivity to anthelmintics, while in the livestock parasite, Haemonchus contortus, anthelmintic use has been shown to increase the expression of ATP transporter genes. These studies as well as others, provide evidence for a potential role of ABC transporters in drug resistance in nematodes. In order to understand more about the family of ABC transporters, we used hidden Markov models to predict ABC transporter proteins from 108 species across the phylum Nematoda and use these data to analyze patterns of diversification and loss in diverse nematode species. We also examined temporal patterns of expression for the ABC transporter family within the filarial nematode Brugia malayi and identify cases of differential expression across diverse life-cycle stages. Taken together, our data provide a comprehensive overview of ABC transporters in diverse nematode species and identify examples of gene loss and diversification in nematodes based on lifestyle and taxonomy.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Genes de Helmintos/genética , Variação Genética , Nematoides/genética , Animais
15.
Int J Parasitol ; 51(5): 321-325, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33421438

RESUMO

Much of the available knowledge of entomopathogenic virulence factors has been gleaned from studies in the nematode parasite Steinernema carpocapsae, but there is good reason to complement this knowledge with similar studies in Heterorhabditis bacteriophora. Three candidate virulence factors from H. bacteriophora have recently been characterised, and each was demonstrated to contribute to infection. This information can be used not only to advance efforts in the biocontrol of insect pests, but also to make inferences about the emergence of parasitism among Clade V nematodes.


Assuntos
Parasitos , Rabditídios , Animais , Insetos , Strongyloidea , Fatores de Virulência/genética
16.
Int J Parasitol ; 51(5): 333-337, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33275943

RESUMO

Nematode Chemosensory G-Protein Coupled Receptors have expanded within nematodes, where they play important roles in foraging and host-seeking behaviour. Nematode Chemosensory G-Protein Coupled Receptors are most highly expressed during free-living stages when chemosensory signalling is required for host detection and nematode activation in various parasitic nematodes, and therefore position Nematode Chemosensory G-Protein Coupled Receptors at the transition from infective to parasitic stages, making them important regulators to study in terms of host-seeking and host specificity. To facilitate the analysis of Nematode Chemosensory G-Protein Coupled Receptors, here we describe an integrative database of nematode chemoreceptors called NemChR-DB. This database enables users to study diverse parasitic nematode chemoreceptors, functionally explore sequence entries through structural and literature-based annotations, and perform cross-species comparisons.


Assuntos
Nematoides , Parasitos , Animais , Receptores Acoplados a Proteínas G/genética , Transdução de Sinais
17.
Comput Biol Chem ; 92: 107464, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33667976

RESUMO

Parasitic nematodes constitute one of the major threats to human health, causing diseases of major socioeconomic importance worldwide. Recent estimates indicate that more than 1 billion people are infected with parasitic nematodes around the world. Current measures to combat parasitic nematode infections include anthelmintic drugs. However, heavy exposure to anthelmintics has selected populations of livestock parasitic nematodes that are no longer susceptible to the drugs, rendering several anthelmintics useless for parasitic nematode control in many areas of the world. The rapidity with which anthelmintic resistance developed in response to these drugs suggests that increasing the selective pressure on human parasitic nematodes will also rapidly generate resistant worm populations. Therefore, development of new anthelmintics is of major importance before resistance becomes widespread in human parasitic nematode populations. G-Protein Coupled Receptors (GPCRs) represent an important target for many pharmacological interventions due to their ubiquitous expression in various cell types. GPCRs contribute to numerous physiological processes, and their ligand binding sites located on cell surfaces make them accessible targets and attractive substrates in terms of druggability. In fact, ∼35 % of Food and Drug Administration (FDA) and European Medicines Agency (EMA) approved drugs target GPCRs and their associated proteins, with over 300 additional drugs targeting GPCRs at the clinical trial stage. Nematode Chemosensory GPCRs (NemChRs) are unique to nematodes, and therefore represent ideal substrates for target-based drug discovery. Here we set out to identify NemChRs that are transcriptionally active inside the host, and to use these NemChRs in a reverse pharmacological screen to impede parasitic development. Our data identified several NemChRs, and we focused on one that was expressed in neuronal cells and exhibited the highest fold change in transcription after host activation. Next, we performed homology modelling and molecular dynamics simulations of this NemChR in order to conduct a virtual screening campaign to identify candidate drug targets which were ranked and selected for experimental testing in bioassays. Taken together, our results identify and characterize a candidate NemChR drug target, and provide a chemogenomic pipeline for identifying nematicide substrates.


Assuntos
Anti-Helmínticos/farmacologia , Rhabditoidea/efeitos dos fármacos , Animais , Anti-Helmínticos/síntese química , Anti-Helmínticos/química , Avaliação Pré-Clínica de Medicamentos , Simulação de Dinâmica Molecular , Testes de Sensibilidade Parasitária
18.
Dev Comp Immunol ; 114: 103820, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32791175

RESUMO

Nematode virulence factors are of interest for a variety of applications including biocontrol against insect pests and the alleviation of autoimmune diseases with nematode-derived factors. In silico "omics" techniques have generated a wealth of candidate factors that may be important in the establishment of nematode infections, although the challenge of characterizing these individual factors in vivo remains. Here we provide a fundamental characterization of a putative lysozyme and serine carboxypeptidase from the host-induced transcriptome of Heterorhabditis bacteriophora. Both factors accelerated the mortality rate following Drosophila melanogaster infections with Photorhabdus luminescens, and both factors suppressed phenoloxidase activity in D. melanogaster hemolymph. Furthermore, the serine carboxypeptidase was lethal to a subpopulation of flies and suppressed the upregulation of antimicrobial peptides as well as phagocytosis. Together, our findings suggest that this serine carboxypeptidase possess both toxic and immunomodulatory properties while the lysozyme is likely to confer immunomodulatory, but not toxic effects.


Assuntos
Carboxipeptidases/metabolismo , Drosophila melanogaster/imunologia , Infecções por Bactérias Gram-Positivas/imunologia , Muramidase/metabolismo , Nematoides/fisiologia , Infecções por Nematoides/imunologia , Photorhabdus/fisiologia , Animais , Imunomodulação , Proteínas de Insetos/metabolismo , Monofenol Mono-Oxigenase/metabolismo , Nematoides/patogenicidade , Virulência
19.
PLoS One ; 15(3): e0230327, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32150746

RESUMO

Sodium Calcium exchanger (NCX) proteins utilize the electrochemical gradient of Na+ to generate Ca2+ efflux (forward mode) or influx (reverse mode). In mammals, there are three unique NCX encoding genes-NCX1, NCX2, and NCX3, that comprise the SLC8A family, and mRNA from all three exchangers is expressed in hippocampal pyramidal cells. Furthermore, mutant ncx2-/- and ncx3-/- mice have each been shown to exhibit altered long-term potentiation (LTP) in the hippocampal CA1 region due to delayed Ca2+ clearance after depolarization that alters synaptic transmission. In addition to the role of NCX at the synapse of hippocampal subfields required for LTP, the three NCX isoforms have also been shown to localize to the dendrite of hippocampal pyramidal cells. In the case of NCX1, it has been shown to localize throughout the basal and apical dendrite of CA1 neurons where it helps compartmentalize Ca2+ between dendritic shafts and spines. Given the role for NCX and calcium in synaptic plasticity, the capacity of NCX splice-forms to influence backpropagating action potentials has clear consequences for the induction of spike-timing dependent synaptic plasticity (STDP). To explore this, we examined the effect of NCX localization, density, and allosteric activation on forward and back propagating signals and, next employed a STDP paradigm to monitor the effect of NCX on plasticity using back propagating action potentials paired with EPSPs. From our simulation studies we identified a role for the sodium calcium exchange current in normalizing STDP, and demonstrate that NCX is required at the postsynaptic site for this response. We also screened other mechanisms in our model and identified a role for the Ca2+ activated K+ current at the postsynapse in producing STDP responses. Together, our data reveal opposing roles for the Na+/Ca2+ exchanger current and the Ca2+ activated K+ current in setting STDP.


Assuntos
Região CA1 Hipocampal/fisiologia , Modelos Neurológicos , Plasticidade Neuronal/fisiologia , Células Piramidais/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Potenciais de Ação/fisiologia , Animais , Região CA1 Hipocampal/citologia , Cálcio/metabolismo , Cátions Bivalentes/metabolismo , Cátions Monovalentes/metabolismo , Simulação por Computador , Modelos Animais , Potássio/metabolismo , Ratos , Sódio/metabolismo
20.
PLoS One ; 15(1): e0228091, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31971963

RESUMO

SWC files are a widely used format to store neuron morphologies, and are used to share digitally reconstructed neurons using NeuroMorpho.org as well as predict functional attributes using simulation environments such as NEURON. Here we set out to develop an easily accessible tool to validate and correct SWC formatted files with an emphasis on high throughput batch processing. SWC_BATCH_CHECK is a package that provides a suite of methods to parse and correct the syntactic structure of a directory of SWC files. This tool ensures that user specified structures such as the soma or basal dendrite are correctly connected while fixing morphological features. This tool will report on missing or invalid data values while also returning basic statistical features for each file. SWC_BATCH_CHECK was validated and tested using thousands of individual SWC files to benchmark runtime performance and efficacy in both reporting on and correcting disparate SWC file features. SWC_BATCH_CHECK is open source and freely available to all users without restriction with guidelines and requirements provided to ensure straightforward installation and execution.


Assuntos
Arquivamento , Neurônios/citologia , Reprodutibilidade dos Testes , Software , Fatores de Tempo
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