Molecular And Biochemical Parasitology[JOURNAL]
Sun
200 papers
Characterization of adjacent charged residues near the agonist binding site of the nematode UNC-49 GABA receptor.
Cochrane E, Foster J, Khatami MH … +2 more , de Haan HW, Forrester SG
Mol Biochem Parasitol · 2022 Nov · PMID 36100173 · Publisher ↗
The UNC-49 receptor is a Cys-loop GABA receptor that is unique to the nematode phylum. The receptor differs from mammalian GABA receptors both in amino acid sequence and pharmacology which highlights its potential as a n...
The UNC-49 receptor is a Cys-loop GABA receptor that is unique to the nematode phylum. The receptor differs from mammalian GABA receptors both in amino acid sequence and pharmacology which highlights its potential as a novel anthelmintic target. Sequence differences within and near the various ligand-binding loops of the nematode receptor suggest that there could be structural differences compared to mammalian receptors that result in different pharmacological and functional features. Here we investigated three residues in the UNC-49 receptor from the parasitic nematode Haemonchus contortus: K181, E183, and T230. Analysis of these residues was conducted via site-directed mutagenesis, electrophysiology, MD simulations, and mutant cycling analysis. In the UNC-49 receptor, E183 lies in close proximity to K181 where together they appear to play a role in GABA sensitivity and pharmacology, possibly interacting via an ionic bond. While the introduction of single alanine residues at each position separately had a negative impact on GABA EC, the double alanine mutant (K181A/E183A) exhibited wildtype-level GABA EC and some differences in pharmacology. Overall, this study has revealed a potentially novel role for these two residues in nematode UNC-49 GABA receptors that could aid in understanding their function.
Alpha-terthienyl increases filamentous actin of Entamoeba histolytica.
Herrera-Martínez M, Hernández-Ramírez VI, Montaño S … +3 more , Chávez-Munguía B, Hernández-Carlos B, Talamás-Rohana P
Mol Biochem Parasitol · 2022 Nov · PMID 36084901 · Publisher ↗
This study aimed to know if alpha terthienyl (α-T) affects E. histolytica viability and to analyze its effect on the actin cytoskeleton. Trophozoites of E. histolytica HM1-IMSS were treated with α-T, then, cell viability...
This study aimed to know if alpha terthienyl (α-T) affects E. histolytica viability and to analyze its effect on the actin cytoskeleton. Trophozoites of E. histolytica HM1-IMSS were treated with α-T, then, cell viability and morphology were evaluated using tetrazolium salts and scanning electron microscopy, respectively; while actin filaments (F-actin) were stained with rhodamine-phalloidin, observed by confocal microscopy and quantified by fluorometry. Data showed that α-T inhibited cell viability of trophozoites (IC, 19.43 µg / mL), affected the cell morphology, and increased the F-actin in a dose-dependent manner. Production of reactive oxygen species and RhoA-GTP levels remained normal in α-T-treated amebas. Two inhibitors that affect the organization of the trophozoites cytoskeleton, one that interacts directly with actin, Cytochalasin D (CD), and one that affects the Rho signaling pathway by inhibiting the downstream effector Rock, Y27632, were tested. Y27632 did not affect the increase of polymerized actin observed with α-T, this compound partially ameliorates the potent disrupting effects of CD on actin filaments. Docking results suggest that α-T could be an antagonist of CD for the same interaction zone in actin, however, more studies are needed to define the action mechanism of this compound.
Is Strongyloides stercoralis hyperinfection induced by glucocorticoids a result of both suppressed host immunity and altered parasite genetics?
Herbert DR, Stoltzfus JDC, Rossi HL … +1 more , Abraham D
Mol Biochem Parasitol · 2022 Sep · PMID 36007683 · Publisher ↗
The gastrointestinal (GI) nematode Strongyloides stercoralis (S.s.) causes human strongyloidiasis, a potentially life-threatening disease that currently affects over 600 million people globally. The uniquely pernicious a...
The gastrointestinal (GI) nematode Strongyloides stercoralis (S.s.) causes human strongyloidiasis, a potentially life-threatening disease that currently affects over 600 million people globally. The uniquely pernicious aspect of S.s. infection, as compared to all other GI nematodes, is its autoinfective larval stage (L3a) that maintains a low-grade chronic infection, allowing undetectable persistence for decades. Infected individuals who are administered glucocorticoid therapy can develop a rapid and often lethal hyperinfection syndrome within days. Hyperinfection patients often present with dramatic increases in first- and second-stage larvae and L3a in their GI tract, with L3a widely disseminating throughout host organs leading to sepsis. How glucocorticoid administration drives hyperinfection remains a critical unanswered question; specifically, it is unknown whether these steroids promote hyperinfection through eliminating essential host protective mechanisms and/or through dysregulating parasite development. This current deficiency in understanding is largely due to the previous absence of a genetically defined mouse model that would support all S.s. life-cycle stages and the lack of successful approaches for S.s. genetic manipulation. However, there are currently new possibilities through the recent demonstration that immunodeficient NOD.Cg-PrkdcIl2rg/SzJ (NSG) mice support sub-clinical infections that can be transformed to lethal hyperinfection syndrome following glucocorticoid administration. This is coupled with advances in transcriptomics, transgenesis, and gene inactivation strategies that now allow rigorous scientific inquiry into S.s. biology. We propose that combining in vivo manipulation of host immunity and deep immunoprofiling strategies with the latest advances in S.s. transcriptomics, piggyBac transposon-mediated transgene insertion, and CRISPR/Cas-9-mediated gene inactivation will facilitate new insights into the mechanisms that could be targeted to block lethality in humans with S.s. hyperinfection.
Aminoacyl-tRNA synthetase (AARS) as an attractive drug target in neglected tropical trypanosomatid diseases-Leishmaniasis, Human African Trypanosomiasis and Chagas disease.
Kushwaha V, Capalash N
Mol Biochem Parasitol · 2022 Sep · PMID 35988745 · Publisher ↗
TriTryp diseases (Leishmaniasis, Human African Trypanosomiasis (HAT), and Chagas disease) are devastating parasitic neglected tropical diseases (NTDs) that affect billions of people in developing countries, cause high mo...
TriTryp diseases (Leishmaniasis, Human African Trypanosomiasis (HAT), and Chagas disease) are devastating parasitic neglected tropical diseases (NTDs) that affect billions of people in developing countries, cause high mortality in humans, and impose a large socio-economic burden. The current treatment options against tritryp diseases are suboptimal and challenging due to the emergence of resistance against available tritryp drugs. Hence, designing and developing effective anti-tritryp drugs with novel targets are required. Aminoacyl-tRNA synthetases (AARSs) involved in specific aminoacylation of transfer RNAs (tRNAs), interrupt protein synthesis through inhibitors, and retard the parasite growth. AaRSs have long been studied as therapeutic targets in bacteria, and three aaRS inhibitors, mupirocin (against IleRS), tavaborole AN2690 (against LeuRS), and halofuginone (against ProRS), are already in clinical practice. The structural differences between tritryp and human aaRSs and the presence of unique sequences (N-terminal domain/C-terminal domain/catalytic domain) make them potential target for developing selective inhibitors. Drugs based on a single aaRS target developed by high-throughput screening (HTS) are less effective due to the emergence of resistance. However, designing multi-targeted drugs may be a better strategy for resistance development. In this perspective, we discuss the characteristics of tritryp aaRSs, sequence conservation in their orthologs and their peculiarities, recent advancements towards the single-target and multi-target aaRS inhibitors developed through rational design.
Strongyloides spp. eliminate male-determining sperm post-meiotically.
Dulovic A, Koch I, Hipp K … +1 more , Streit A
Mol Biochem Parasitol · 2022 Sep · PMID 35985494 · Publisher ↗
If normal male meiosis occurs, it would be expected that 50 % of sperm lack an X chromosome (nullo X) and hence upon fertilisation, result in male progeny. However, for sexual reproduction within the free-living stages o...
If normal male meiosis occurs, it would be expected that 50 % of sperm lack an X chromosome (nullo X) and hence upon fertilisation, result in male progeny. However, for sexual reproduction within the free-living stages of Strongyloides spp. male offspring are absent. We had shown earlier by quantitative whole genome sequencing that within Strongyloides spp., nullo-X sperm are either absent (S. papillosus) or underrepresented (S. ratti) among mature sperm. To investigate how and when this elimination of male-determining sperm occurs, we characterised spermatogenesis and the dynamic localisation of important molecular players such as tubulin, actin and major sperm protein by DIC microscopy, immunohistochemistry, and fluorescent in situ hybridization (FISH) in S. ratti, S. papillosus and Parastrongyloides trichosuri. We found that meiotic divisions in these parasites proceeded as expected for organisms with XO males, resulting in four equally sized spermatocytes, two with and two without an X chromosome. However, mature sperm were found to almost always contain an X chromosome. We also observed structures that contained protein constituents of sperm, such as actin and major sperm protein (MSP) but no DNA. These structures resemble C. elegans residual bodies in appearance and may assume their function. We hypothesize that spermatocytes without an X-chromosome undergo some form of programmed cell death and transform into these residual body-like structures. As in C. elegans, MSP is found in fibrous body-membranous organelles (FB-MOs). Knocking down MSP by RNAi showed that MSP is essential for fertility in S. ratti, as it is in C. elegans.
Deleting ku80 improves the efficiency of targeted gene editing in Neospora caninum.
Wu K, Song X, Wu Y … +3 more , Yang X, Liu J, Liu Q
Mol Biochem Parasitol · 2022 Sep · PMID 35963548 · Publisher ↗
CRISPR/Cas9 technology has been widely used for gene editing in organisms. Gene deletion of the ku80/ku70 complex can improve the efficiency of gene replacement in Arabidopsis thaliana, Cryptococcus neoformans, and Toxop...
CRISPR/Cas9 technology has been widely used for gene editing in organisms. Gene deletion of the ku80/ku70 complex can improve the efficiency of gene replacement in Arabidopsis thaliana, Cryptococcus neoformans, and Toxoplasma gondii, which remained elusive in Neospora caninum. Here, we knock out the ku80 gene in Nc1 strain by using CRISPR/Cas9, detect the growth rate and virulence of NcΔku80. Then we compare the efficiency of gene replacements between NcΔku80 and Nc1 strains by transfected with the same HA-tagged plasmids, and the percentage of HA-tagged parasites was investigated by IFA. The results showed that gene targeting efficiency was increased in the NcΔku80 strain via double crossover at several genetic loci, but its growth rate and virulence were unaffected. In conclusion, the NcΔku80 strain can be used as an effective strain for rapid gene editing of N. caninum.
Stress-responsive AMP Kinase like protein regulates encystation of Entamoeba invadens.
Goswami P, Samanta SK, Agarwal T … +1 more , Ghosh SK
Mol Biochem Parasitol · 2022 Sep · PMID 35870645 · Publisher ↗
Starvation is always accompanied by an increase in the ratio of AMP/ATP followed by activation of AMPK. It is one of the sensors for cellular energy status and is highly conserved across various species. Its role in the...
Starvation is always accompanied by an increase in the ratio of AMP/ATP followed by activation of AMPK. It is one of the sensors for cellular energy status and is highly conserved across various species. Its role in the stage differentiation process of protozoan species like Giardia, Plasmodium, Trypanosome, and Toxoplasma has been reported. Since Entamoeba undergoes encystation in glucose-starved conditions; it intrigued us to investigate the existence and role of AMPK during the differentiation of trophozoites to the cyst. By employing in silico approaches, we have identified an AMPK homologue which is denominated here as EiAMPK (AMPK-like protein in Entamoeba invadens). Sequence and structural analysis indicate that EiAMPK is sequentially and structurally similar to the AMPK alpha subunit of other organisms. The recombinant form of EiAMPK was functionally active and in accordance, its activity was inhibited by an AMPK-specific inhibitor (eg. Compound C). The increased expression of EiAMPK during different stresses indicated that EiAMPK is a stress-responsive gene. To further investigate, whether EiAMPK has any role in encystation, we employed RNAi-mediated gene silencing that demonstrated its active involvement in encystation. It is known that Entamoeba maintains a flow of glucose from the glycolytic pathway to chitin synthesis for cyst wall formation during encystation. It is conceivable that EiAMPK might have a command over such glucose metabolism. As anticipated, the chitin synthesis was found greatly inhibited in both EiAMPK knockdown and Compound C treated cells, indicating that EiAMPK regulates the cyst wall chitin synthesis.
Inorganic phosphate transporter in Giardia duodenalis and its possible role in ATP synthesis.
Carvalho-de-Araújo AD, Carvalho-Kelly LF, Dick CF … +1 more , Meyer-Fernandes JR
Mol Biochem Parasitol · 2022 Sep · PMID 35843419 · Publisher ↗
Giardia duodenalis is a flagellated protozoan that inhabits vertebrate host intestines, causing the disease known as giardiasis. Similar to other parasites, G. duodenalis must take advantage of environmental resources to...
Giardia duodenalis is a flagellated protozoan that inhabits vertebrate host intestines, causing the disease known as giardiasis. Similar to other parasites, G. duodenalis must take advantage of environmental resources to survive, such as inorganic phosphate (P) availability. P is an anionic molecule and an essential nutrient for all organisms because it participates in the biosynthesis of biomolecules, energy storage, and cellular structure formation. The first step in Pi metabolism is its uptake through specific transporters on the plasma membrane. We identified a symporter H:P-type ORF sequence in the G. duodenalis genome (GenBank ID: GL50803_5164), named GdPho84, which is homologous to Saccharomyces cerevisiae PHO84. In trophozoites, P transport was linear for up to 15 min, and the cell density was 3 × 10 cells/ml. Physiological variations in pH (6.4-8.0) did not influence P uptake. This P transporter had a high affinity, with K = 67.7 ± 7.1 µM P. SCH28080 (inhibitor of H, K-ATPase), bafilomycin A (inhibitor of vacuolar H-ATPase), and FCCP (H ionophore) were able to inhibit P transport, indicating that an H gradient in the cell powered uphill P movement. PAA, an H-dependent P transport inhibitor, reduced cell proliferation, P transport activity, and GdPHO48 mRNA levels. P starvation stimulated membrane potential-sensitive P uptake coupled to H fluxes, increased GdPho84 expression, and reduced intracellular ATP levels. These events indicate that these cells had an increased capacity to internalize P as a compensatory mechanism compared to cells maintained in control medium conditions. Internalized P can be used in glycolytic metabolism once iodoacetamide (GAPDH inhibitor) inhibits P influx. Together, these results reinforce the hypothesis that P is a crucial nutrient for G. duodenalis energy metabolism.
Schistosomiasis related circulating cell-free DNA: A useful biomarker in diagnostics.
Ullah H, Arbab S, Li K … +3 more , Khan MIU, Qadeer A, Muhammad N
Mol Biochem Parasitol · 2022 Sep · PMID 35835258 · Publisher ↗
Schistosoma is a genus of trematodes causing schistosomiasis, a major neglected tropical disease infecting more than 240 million people and with 700 million people at the risk of infection in the tropical and subtropical...
Schistosoma is a genus of trematodes causing schistosomiasis, a major neglected tropical disease infecting more than 240 million people and with 700 million people at the risk of infection in the tropical and subtropical regions of the world, especially low-income countries. For the elimination of the disease, accurate diagnostic tools are needed. Besides allowing early treatment, early detection prevents environmental contamination and in turn ensures safe water sources in the endemic areas. Cell-free DNA (cfDNA) biomarker detection is a relatively new tool, used for the diagnosis of schistosomiasis in the early stages of infection from non-invasive clinical or experimental samples. cfDNA can be detected in Schistosoma infected host body fluids such as urine, serum, saliva and tissues, mainly in blood offering significant benefits for accurate diagnosis. In the current review, we described different characteristics of cfDNA, evidencing and supporting its potential uses in Schistosoma diagnosis and the improvement of treatment effectiveness.
Increased iron uptake in the bladder wall of racemose cysts of Taenia solium.
Orrego MA, Vasquez CM, Togneri K … +4 more , Laclette JP, Garcia HH, Nash TE, Cysticercosis Working Group in Peru
Mol Biochem Parasitol · 2022 Sep · PMID 35830923 · Full text
Racemose neurocysticercosis is an aggressive infection caused by the aberrant expansion and proliferation of the bladder wall of the Taenia solium cyst within the subarachnoid spaces of the human brain. The parasite deve...
Racemose neurocysticercosis is an aggressive infection caused by the aberrant expansion and proliferation of the bladder wall of the Taenia solium cyst within the subarachnoid spaces of the human brain. The parasite develops and proliferates in a microenvironment with low concentrations of growth factors and micronutrients compared to serum. Iron is important for essential biological processes, but its requirement for racemose cyst viability and proliferation has not been studied. The presence of iron in the bladder wall of racemose and normal univesicular T. solium cysts was determined using Prussian blue staining. Iron deposits were readily detected in the bladder wall of racemose cysts but were not detectable in the bladder wall of univesicular cysts. Consistent with this finding, the genes for two iron-binding proteins (ferritin and melanotransferrin) and ribonucleotide reductase were markedly overexpressed in the racemose cyst compared to univesicular cysts. The presence of iron in the bladder wall of racemose cysts may be due to its increased metabolic rate due to proliferation.
Anisakis spp, DNA detection in paraffin-embedded tissue biopsies recovered from patients with gastritis using real-time PCR in Bushehr, Persian Gulf, Iran.
Najjari M, Sadjjadi SM, Khodadadi H … +2 more , Farzaneh MR, Mattiucci S
Mol Biochem Parasitol · 2022 Sep · PMID 35817309 · Publisher ↗
Anisakiasis is a zoonotic fish-born parasitic disease caused by anisakid nematodes. Paraffin-embedded blocks containing biopsy samples taken from patients suffering gastritis with unknown causes were investigated by real...
Anisakiasis is a zoonotic fish-born parasitic disease caused by anisakid nematodes. Paraffin-embedded blocks containing biopsy samples taken from patients suffering gastritis with unknown causes were investigated by real-time PCR, in the Bushehr region, Iran; where human anisakiasis has not been reported, so far. A total of 50 paraffin-embedded blocks were randomly selected from 250 archived blocks of the patients with gastritis. A SYBER green-based real-time PCR targeting the ITS1 region was developed for the identification of Anisakis genus. An 86 bp partial fragment of the Anisakis spp. ITS1 gene was amplified successfully. A total of 3 out of 50 samples (6 %) had positive amplification in the samples and their pathology reports showed a significant finding of moderate chronic gastritis with or without ulcers. In conclusion, the developed qPCR could be used for detecting Anisakis spp. larval DNA in human biopsy blocks. This study showed the hidden human cases of anisakiasis in the Bushehr for the first time.
Antiamoebic properties of salicylic acid-based deep eutectic solvents for the development of contact lens disinfecting solutions against Acanthamoeba.
Siddiqui R, Makhlouf Z, Akbar N … +4 more , Khamis M, Ibrahim T, Khan AS, Khan NA
Mol Biochem Parasitol · 2022 Jul · PMID 35753525 · Publisher ↗
Acanthamoeba castellanii is a protist pathogen that can cause sight-threatening keratitis and a fatal infection of the central nervous system, known as granulomatous amoebic encephalitis. In this study, effects of five m...
Acanthamoeba castellanii is a protist pathogen that can cause sight-threatening keratitis and a fatal infection of the central nervous system, known as granulomatous amoebic encephalitis. In this study, effects of five malonic acid and salicylic acid-based deep eutectic solvents (DES) on A. castellanii were investigated. These are salicylic acid-trioctylphosphine (DES 1), salicylic acid- trihexylamine (DES 2), salicylic acid-trioctylamine (DES 3), malonic acid-trioctylphosphine (DES 4) and malonic acid-trihexylamine (DES 5). The experiments were done by performing amoebicidal, encystment, excystment, cytopathogenicity, and cytotoxicity assays. At micromolar dosage, the solvents DES 2 and DES 3 displayed significant amoebicidal effects (P < 0.05), inhibited encystment and excystment, undermined the cell-mediated cytopathogenicity of A. castellanii, and also displayed minimal cytotoxicity to human cells. Conversely, the chemical components of these solvents: salicylic acid, trihexylamine, and trioctylamine showed minimal effects when tested individually. These results are very promising and to the best of our knowledge, are reported for the first time on the effects of deep eutectic solvents on amoebae. These results can be applied in the development of new formulations of novel contact lens disinfectants against Acanthamoeba castellanii.
Evaluation of nanoparticles with 5-fluorouracil and chloroquine on Acanthamoeba castellanii activity.
Saeed BQ, Qalaji MR, Akbar N … +7 more , Siddiqui R, Roberta C, Manzoor S, Muhammad JS, Adrees AO, Al-Shahrabi R, Khan NA
Mol Biochem Parasitol · 2022 Jul · PMID 35714753 · Publisher ↗
Acanthamoeba is opportunistic pathogens that cause vision-threatening Acanthamoeba keratitis (AK). Previous studies proposed the use of chloroquine (CQ) and 5-fluorouracil (5FU) as anti-Acanthamoeba agents. The objective...
Acanthamoeba is opportunistic pathogens that cause vision-threatening Acanthamoeba keratitis (AK). Previous studies proposed the use of chloroquine (CQ) and 5-fluorouracil (5FU) as anti-Acanthamoeba agents. The objective of this study was to determine the benefit of using 5FU and CQ nanoparticles (NP) formulations against A. castellanii that belonging to the T4 genotype and evaluate their anti-Acanthamoebic characteristic. Triplicate batches of 5FU nanoparticles (5FU-NP) were synthesized by using a modified nanoprecipitation method, while CQ nanoparticles (CQ-NP) synthesized using a modified double emulsion method. The synthesized nanoparticles were subjected to biological assays to investigate their amoebicidal, amoebistatic, anti-encystation, and anti-excystation effects against A. castellanii, as well as cell cytotoxicity. Cytotoxicity assays were performed using human keratinocyte cells (HaCaT) to determine the effect of CQ and 5FU nanoformulations on host cells. 5FU-NP with a concentration of 60 µM showed significant inhibition to amoeba binding into human cell lines and remarkable prevention mainly during the encystation stage. Moreover, 5FU-NP resulted in less cytotoxicity and pathogenicity when compared with the free 5FU. On the other hand, CQ and CQ-NP, at the same concentration, showed poor inhibition to amoeba binding into human cells and insignificant prevention to encystation stage. Moderate human cells damage was resulted following their treatment with CQ and CQ-NP. In conclusion, 5FU may have the potential as an antiamoebic agent against Acanthamoeba spp. preferably as a nanoformulation to enhance its activity and reduce its cytoxicity.
The 'nuclear option' revisited: Confirmation of Ss-daf-12 function and therapeutic potential in Strongyloides stercoralis and other parasitic nematode infections.
Lok JB, Kliewer SA, Mangelsdorf DJ
Mol Biochem Parasitol · 2022 Jul · PMID 35697206 · Publisher ↗
Mechanisms governing morphogenesis and development of infectious third-stage larvae (L3i) of parasitic nematodes have been likened to those regulating dauer development in Caenorhabditis elegans. Dauer regulatory signal...
Mechanisms governing morphogenesis and development of infectious third-stage larvae (L3i) of parasitic nematodes have been likened to those regulating dauer development in Caenorhabditis elegans. Dauer regulatory signal transduction comprises initial G protein-coupled receptor (GPCR) signaling in chemosensory neurons of the amphidial complex that regulates parallel insulin- and TGFβ-like signaling in the tissues. Insulin- and TGFβ-like signals converge to co-regulate steroid signaling through the nuclear receptor (NR) DAF-12. Discovery of the steroid ligands of DAF-12 opened a new avenue of small molecule physiology in C. elegans. These signaling pathways are conserved in parasitic nematodes and an increasing body of evidence supports their function in formation and developmental regulation of L3i during the infectious process in soil transmitted species. This review presents these lines of evidence for G protein-coupled receptor (GPCR), insulin- and TGFβ-like signaling in brief and focuses primarily on signaling through parasite orthologs of DAF-12. We discuss in some depth the deployment of sensitive analytical techniques to identify Δ7-dafachronic acid as the natural ligand of DAF-12 homologs in Strongyloides stercoralis and Haemonchus contortus and of targeted mutagenesis by CRISPR/Cas9 to assign dauer-like regulatory function to the NR Ss-DAF-12, its coactivator Ss-DIP-1 and the key ligand biosynthetic enzyme Ss-CYP-22a9. Finally, we present published evidence of the potential of Ss-DAF-12 signaling as a chemotherapeutic target in human strongyloidiasis.
Using newly optimized genetic tools to probe Strongyloides sensory behaviors.
Mendez P, Walsh B, Hallem EA
Mol Biochem Parasitol · 2022 Jul · PMID 35697205 · Full text
The oft-neglected human-parasitic threadworm, Strongyloides stercoralis, infects roughly eight percent of the global population, placing disproportionate medical and economic burden upon marginalized communities. While c...
The oft-neglected human-parasitic threadworm, Strongyloides stercoralis, infects roughly eight percent of the global population, placing disproportionate medical and economic burden upon marginalized communities. While current chemotherapies treat strongyloidiasis, disease recrudescence and the looming threat of anthelminthic resistance necessitate novel strategies for nematode control. Throughout its life cycle, S. stercoralis relies upon sensory cues to aid in environmental navigation and coordinate developmental progression. Odorants, tastants, gases, and temperature have been shown to shape parasite behaviors that drive host seeking and infectivity; however, many of these sensory behaviors remain poorly understood, and their underlying molecular and neural mechanisms are largely uncharacterized. Disruption of sensory circuits essential to parasitism presents a promising strategy for future interventions. In this review, we describe our current understanding of sensory behaviors - namely olfactory, gustatory, gas sensing, and thermosensory behaviors - in Strongyloides spp. We also highlight the ever-growing cache of genetic tools optimized for use in Strongyloides that have facilitated these findings, including transgenesis, CRISPR/Cas9-mediated mutagenesis, RNAi, chemogenetic neuronal silencing, and the use of fluorescent biosensors to measure neuronal activity. Bolstered by these tools, we are poised to enter an era of rapid discovery in Strongyloides sensory neurobiology, which has the potential to shape pioneering advances in the prevention and treatment of strongyloidiasis.
A single amino acid substitution alters activity and specificity in Plasmodium falciparum aspartyl & asparaginyl-tRNA synthetases.
Sharma VK, Gupta S, Chhibber-Goel J … +2 more , Yogavel M, Sharma A
Mol Biochem Parasitol · 2022 Jul · PMID 35644266 · Publisher ↗
The specificity of each aminoacyl-tRNA synthetase (aaRS) for its cognate amino acid ensures correct tRNA esterification and allows fidelity in protein synthesis. The aaRSs discriminate based on the chemical properties of...
The specificity of each aminoacyl-tRNA synthetase (aaRS) for its cognate amino acid ensures correct tRNA esterification and allows fidelity in protein synthesis. The aaRSs discriminate based on the chemical properties of their amino acid substrates and structural features of the binding pockets. In this study, we characterized aspartyl-(DRS) and asparaginyl-tRNA synthetase (NRS) from Plasmodium falciparum to determine the basis of their specificity towards L-asp and L-asn respectively. The negatively charged L-asp and its analogue L-asn differ only in their side-chain groups i.e., -OH and -NH. Further, the amino acid binding sites are highly conserved within these two enzymes. Analysis of the substrate (L-asp/L-asn) binding sites across species revealed two highly conserved residues in PfDRS (D408 and K372) and PfNRS (E395 and L360) that are involved in recognition of the O/N of L-asp/L-asn respectively. These residues were mutated and swapped between the D408→E in PfDRS and the corresponding E395→D in PfNRS. A similar approach was employed for residue number K372→L in PfDRS and L360→K in PfNRS. The mutated PfDRS retained its enzymatic activity during step 1 of aminoacylation reaction towards L-asp and L-asn and esterified tRNA with L-asp like wild type enzyme, while the PfDRS was rendered enzymatically inactive. The correspondingly mutated PfNRS was enzymatically inactive. The mutated PfNRS had an altered specificity and esterified tRNA with non-cognate amino acid L-asp and not L-asn. These data suggest that the residue K372 is crucial for the enzymatic activity of PfDRS while the residue L360 in PfNRS imparts specificity towards L-asn.
Transient expression of a luciferase mRNA in plant-parasitic and free-living nematodes by electroporation.
Thekke-Veetil T, McCoppin NK, Domier LL … +4 more , Hajimorad MR, Lambert KN, Lim HS, Hartman GL
Mol Biochem Parasitol · 2022 Jul · PMID 35640846 · Publisher ↗
Despite their economic significance in agricultural cropping systems, a lack of suitable molecular tools for manipulating gene expression has hindered progress in the functional genomics of plant parasitic nematodes (PPN...
Despite their economic significance in agricultural cropping systems, a lack of suitable molecular tools for manipulating gene expression has hindered progress in the functional genomics of plant parasitic nematodes (PPN). Obligate sexual reproduction and the obligate nature of PPN-host interactions further complicate the development of in vivo gene delivery and expression systems in these pests. Methods such as microinjection and microprojectile bombardment have been developed for introducing gene constructs into the free-living nematode, Caenorhabditis elegans. However, these procedures can be laborious and inefficient. Electroporation has been used extensively to introduce macromolecules, including single-stranded RNAs, into eukaryotic and prokaryotic cells. The technique has also been used for the delivery of DNA and double-stranded RNA constructs into nematodes by whole-animal electroporation. Here, we describe methods for the expression of a nematode-optimized NanoLuc luciferase mRNA in the form of in vitro transcripts following whole-animal electroporation of Heterodera glycines, Meloidogyne incognita, and C. elegans. The ability to transiently express single-stranded RNA constructs in economically important PPN provides a rapid means to evaluate nematode and/or foreign genes for their biological significance and potential role in nematode management.
Advances in Plasmodium research, an update: Highlights from the Malaria in Melbourne 2021 conference.
Adderley J, Boulet C, McCann K … +3 more , McHugh E, Ioannidis LJ, Yeoh LM
Mol Biochem Parasitol · 2022 Jul · PMID 35605814 · Publisher ↗
The Malaria in Melbourne 2021 conference was held online in October. This conference aims to provide a platform for students and early career researchers to share their research and develop new collaborative networks. Th...
The Malaria in Melbourne 2021 conference was held online in October. This conference aims to provide a platform for students and early career researchers to share their research and develop new collaborative networks. The program covered a broad range of topics including antimalarial drug development, epidemiology, immunology, molecular and cellular biology, and other emerging technologies. This article summarises recent advances in Plasmodium research presented at the Malaria in Melbourne 2021 conference.
Effect of berberine on copper and zinc levels in chickens infected with Eimeria tenella.
Huang Z, Zhang X, Zhu Q … +4 more , Cao F, Liu W, Shi P, Yang X
Mol Biochem Parasitol · 2022 May · PMID 35561873 · Publisher ↗
Berberine, a traditional Chinese medicine, was found to exhibit anticoccidial activity. However, its mechanism is unclear. Trace metals such as copper and zinc are extremely low (less than 0.01% of the total weight of th...
Berberine, a traditional Chinese medicine, was found to exhibit anticoccidial activity. However, its mechanism is unclear. Trace metals such as copper and zinc are extremely low (less than 0.01% of the total weight of the body) but play a vital role in organisms. In the present study, we investigated the effect of berberine on copper and zinc levels in chickens infected with Eimeria tenella. Firstly, our data confirmed that infected chickens with E. tenella exhibited classic impairment on the 8th day of post infection, such as weight loss and increased feed conversion. Further study showed that E. tenella infection decreased the contents of copper and zinc in the liver and serum of chickens. Berberine was similar to amprolium and significantly improved the pathogenic conditions. Berberine could restore copper and zinc imbalance caused by E. tenella in chickens to a large extent. Studies on the development of cecum lesions demonstrated that the protective effect of berberine on the intestinal cecum was similar to that of the Cu/Zn mixture. Additionally, the mRNA expression of several metal transport related genes of the chick small intestine, including zinc transporter 1, copper transporter 1 and divalent metal ion transporter 1, was elevated by the treatment with berberine. Taken together, we speculate that the anticoccidial activity of berberine may be related to the maintenance of certain metals (Cu/Zn) homeostasis by affecting mRNA expression of their transport genes. However, the mode of action of BBR on these vital metals in the chicks infected with E. tenella still needs to be further studied.
Approaches to studying the developmental switch of Strongyloides - Moving beyond the dauer hypothesis.
Viney M, Morris R
Mol Biochem Parasitol · 2022 May · PMID 35413360 · Publisher ↗
Strongyloides' developmental switch between direct, parasitic and indirect, free-living development has intrigued, confused, and fascinated biologists since it was first discovered more than 100 years ago. Proximately, t...
Strongyloides' developmental switch between direct, parasitic and indirect, free-living development has intrigued, confused, and fascinated biologists since it was first discovered more than 100 years ago. Proximately, the switch is controlled by environmental conditions that developing larvae are exposed to, but genotypes differ in their sensitivity to these cues. Ultimately, selection will act on this switch to generate a direct vs. indirect phenotype that maximises a genotype's fitness, but we have a poor understanding of the relative fitness advantages of these different routes of development. Mechanistically, the switch senses and transduces environmental cues, integrates signals that are then used to make a developmental decision which is then enacted. Seeking to understand the molecular form of this process has focussed on the C. elegans dauer hypothesis, but this has been found to be wanting. So, we argue that the time has come to move beyond the dauer hypothesis and better refine our question to ask: What is it that controls the variation in developmental switching among Strongyloides genotypes? We discuss approaches to achieve this research aim that now lies within our grasp.
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