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Shang Kuan TC, Prichard RK. Developmental regulation of Dirofilaria immitis microfilariae and evaluation of ecdysone signaling pathway transcript level using droplet digital PCR. Parasit Vectors 2020; 13:614. [PMID: 33298156 PMCID: PMC7724712 DOI: 10.1186/s13071-020-04480-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/07/2020] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Current measures for the prevention of dirofilariasis, caused by the dog heartworm, Dirofilaria immitis, rely on macrocyclic lactones, but evidence of drug-resistant isolates has called for alternative approaches to disease intervention. As microfilariae are known to be in a state of developmental arrest in their mammalian host and then undergo two molts once inside the arthropod, the aim of this study was to look at the developmental regulation of D. immitis microfilariae that occurs in their arthropod host using in vitro approaches and to investigate the role of the ecdysone signaling system in this development regulation. METHODS Dirofilaria immitis microfilariae extracted from dog blood were incubated under various culture conditions to identify those most suitable for in vitro culture and development of the microfilariae, and to determine the effects of fetal bovine serum (FBS), mosquito cells, and ecdysteroid on the development of the microfilariae. Transcript levels of the ecdysone signaling pathway components were measured with droplet digital PCR (ddPCR). RESULTS In vitro conditions that best promote early development of D. immitis microfilariae to the "late sausage stage" have been identified, although shedding of the cuticle was not observed. FBS had inhibitory effects on the development and motility of the microfilariae, but media conditioned with Anopheles gambiae cells were favorable to microfilarial growth. The transcript level study using ddPCR also showed that ecdysone signaling system components were upregulated in developing microfilariae and that 20-hydroxyecdysone increased the proportion of larvae developing to the sausage and late sausage stages in vitro. CONCLUSIONS The arthropod host environment provides cues required for the rapid development of D. immitis microfilariae, and the ecdysone signaling system may play an important role in filarial nematode developmental transitions. This study contributes to a better understanding of the developmental process of D. immitis microfilariae.
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Affiliation(s)
- Tsai-Chi Shang Kuan
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, Montreal, H9X3V9, Canada.
| | - Roger K Prichard
- Institute of Parasitology, McGill University, Sainte-Anne-de-Bellevue, Montreal, H9X3V9, Canada.
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May K, Scheper C, Brügemann K, Yin T, Strube C, Korkuć P, Brockmann GA, König S. Genome-wide associations and functional gene analyses for endoparasite resistance in an endangered population of native German Black Pied cattle. BMC Genomics 2019; 20:277. [PMID: 30961534 PMCID: PMC6454736 DOI: 10.1186/s12864-019-5659-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 03/29/2019] [Indexed: 12/14/2022] Open
Abstract
Background Gastrointestinal nematodes (GIN), liver flukes (Fasciola hepatica) and bovine lungworms (Dictyocaulus viviparus) are the most important parasitic agents in pastured dairy cattle. Endoparasite infections are associated with reduced milk production and detrimental impacts on female fertility, contributing to economic losses in affected farms. In quantitative-genetic studies, the heritabilities for GIN and F. hepatica were moderate, encouraging studies on genomic scales. Genome-wide association studies (GWAS) based on dense single nucleotide polymorphism (SNP) marker panels allow exploration of the underlying genomic architecture of complex disease traits. The current GWAS combined the identification of potential candidate genes with pathway analyses to obtain deeper insights into bovine immune response and the mechanisms of resistance against endoparasite infections. Results A 2-step approach was applied to infer genome-wide associations in an endangered dual-purpose cattle subpopulation [Deutsches Schwarzbuntes Niederungsrind (DSN)] with a limited number of phenotypic records. First, endoparasite traits from a population of 1166 Black and White dairy cows [including Holstein Friesian (HF) and DSN] naturally infected with GIN, F. hepatica and D. viviparus were precorrected for fixed effects using linear mixed models. Afterwards, the precorrected phenotypes were the dependent traits (rFEC-GIN, rFEC-FH, and rFLC-DV) in GWAS based on 423,654 SNPs from 148 DSN cows. We identified 44 SNPs above the genome-wide significance threshold (pBonf = 4.47 × 10− 7), and 145 associations surpassed the chromosome-wide significance threshold (range: 7.47 × 10− 6 on BTA 1 to 2.18 × 10− 5 on BTA 28). The associated SNPs identified were annotated to 23 candidate genes. The DAVID analysis inferred four pathways as being related to immune response mechanisms or involved in host-parasite interactions. SNP effect correlations considering specific chromosome segments indicate that breeding for resistance to GIN or F. hepatica as measured by fecal egg counts is genetically associated with a higher risk for udder infections. Conclusions We detected a large number of loci with small to moderate effects for endoparasite resistance. The potential candidate genes regulating resistance identified were pathogen-specific. Genetic antagonistic associations between disease resistance and productivity were specific for specific chromosome segments. The 2-step approach was a valid methodological approach to infer genetic mechanisms in an endangered breed with a limited number of phenotypic records. Electronic supplementary material The online version of this article (10.1186/s12864-019-5659-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Katharina May
- Institute of Animal Breeding and Genetics, Justus-Liebig-University of Gießen, 35390, Gießen, Germany.,Institute for Parasitology, Center for Infection Medicine, University of Veterinary Medicine Hanover, 30559, Hannover, Germany
| | - Carsten Scheper
- Institute of Animal Breeding and Genetics, Justus-Liebig-University of Gießen, 35390, Gießen, Germany
| | - Kerstin Brügemann
- Institute of Animal Breeding and Genetics, Justus-Liebig-University of Gießen, 35390, Gießen, Germany
| | - Tong Yin
- Institute of Animal Breeding and Genetics, Justus-Liebig-University of Gießen, 35390, Gießen, Germany
| | - Christina Strube
- Institute for Parasitology, Center for Infection Medicine, University of Veterinary Medicine Hanover, 30559, Hannover, Germany
| | - Paula Korkuć
- Department for Crop and Animal Sciences, Breeding Biology and Molecular Genetics, Faculty of Live Science, Humboldt-Universität of Berlin, 10115, Berlin, Germany
| | - Gudrun A Brockmann
- Department for Crop and Animal Sciences, Breeding Biology and Molecular Genetics, Faculty of Live Science, Humboldt-Universität of Berlin, 10115, Berlin, Germany
| | - Sven König
- Institute of Animal Breeding and Genetics, Justus-Liebig-University of Gießen, 35390, Gießen, Germany.
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Schumann I, Kenny N, Hui J, Hering L, Mayer G. Halloween genes in panarthropods and the evolution of the early moulting pathway in Ecdysozoa. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180888. [PMID: 30839709 PMCID: PMC6170570 DOI: 10.1098/rsos.180888] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 08/17/2018] [Indexed: 05/15/2023]
Abstract
Moulting is a characteristic feature of Ecdysozoa-the clade of moulting animals that includes the hyperdiverse arthropods and less speciose groups, such as onychophorans, tardigrades and nematodes. Moulting has been best analysed in arthropods, specifically in insects and crustaceans, in which a complex neuroendocrine system acts at the genomic level and initiates the transcription of genes responsible for moulting. The key moulting hormones, ecdysone and 20-hydroxyecdysone, are subsequently synthesized from cholesterol ingested with food. Their biosynthesis is regulated by the Rieske-domain protein Neverland and cytochrome P450 enzymes encoded by the so-called 'Halloween' genes. Ecdysone is then released into the haemolymph and modified into 20-hydroxyecdysone, which binds to the nuclear receptor EcR/USP and initiates transcription of the Early genes. As little is known about the moulting pathway of other ecdysozoans, we examined the occurrence of genes involved in ecdysteroid biosynthesis and the early moulting cascade across ecdysozoan subgroups. Genomic and transcriptomic searches revealed no Halloween genes in cycloneuralians, whereas only shadow (CYP315A1) is present in onychophorans and tardigrades, suggesting that the Halloween genes evolved stepwise in panarthropods. These findings imply that the genes which were responsible for the ecdysteroid biosynthesis in the last common ancestor of Ecdysozoa are currently unknown.
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Affiliation(s)
- Isabell Schumann
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
- Molecular Evolution and Animal Systematics, Institute of Biology, University of Leipzig, Leipzig, Germany
| | - Nathan Kenny
- School of Life Sciences, Simon F.S. Li Marine Science Laboratory, Center of Soybean Research, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China
| | - Jerome Hui
- School of Life Sciences, Simon F.S. Li Marine Science Laboratory, Center of Soybean Research, State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China
| | - Lars Hering
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Kassel, Germany
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Patricio-Gómez JM, Valdez RA, Veloz A, Aguilar-Vega L, Zurabian R, Romano MC. The synthesis of steroids by Taenia crassiceps WFU cysticerci and tapeworms is related to the developmental stages of the parasites. Gen Comp Endocrinol 2018; 259:154-160. [PMID: 29174867 DOI: 10.1016/j.ygcen.2017.11.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 11/20/2017] [Accepted: 11/21/2017] [Indexed: 11/19/2022]
Abstract
Taeniids tapeworms are hermaphroditic helminths that gradually develop testis and ovaries in their reproductive units. The larval stage of the tapeworms named cysticercus is a vesicle that contains the scolex and proliferates asexually in the abdominal cavity of mice. Once in the host, they evaginate, attach to the gut and develop into an adult organism, the tapeworm. We have previously reported reported that T. crassiceps ORF and solium cysticerci transform steroid precursors to androgens and estrogens. Taenia crassiceps WFU cysticerci can also synthesize corticosteroids. The aim of the present work is to investigate the relationship between steroid synthesis ability and the developmental stage of the parasite T. crassiceps WFU. To this purpose, cysticerci were obtained from the abdominal cavity of female mice, manually separated in invaginated (IC) and evaginated parasites (EC) and preincubated for 24 h in DMEM plus antibiotics/antimycotics. Next step consisted in incubation for different periods in the fresh media added with tritiated androstenedione (3H-A4) or progesterone (3H-P4) and incubated for different periods. Taenia crassiceps WFU tapeworms were recovered from the intestine of golden hamsters that had been orally infected with cysticerci. The worms were pre-cultured in DMEM plus FBS and antibiotics, and then incubated without FBS for different time periods, in the presence of 3H-A4 or 3H-P4. At the end of the experiments the media from cysticerci and tapeworms were analyzed by thin layer chromatography. Results showed that testosterone synthesis was significantly higher in the evaginated cysticerci and increased with time in culture. The invaginated and evaginated cysticerci also synthesized small quantities of 17ß-estradiol (E2) and estrone. The evaginated cysticerci synthesized twice more 3H-deoxycorticosterone (3H-DOC) than the invaginated parasites, the production increased significantly with time in culture. Taenia crassiceps WFU tapeworms synthesized significant quantities of 3H-testosterone and small amounts of estrone after only 3 h of culture in the presence of 3H-A4. The tapeworms also transformed 3H-P4 to 3H-DOC and increased its synthesis after 24 h in culture. In summary, our data show the pathways that T. crassiceps WFU cysticerci use to synthesize sexual steroids in both larval developmental stages and reveals the steroidogenic capacity of the tapeworms.
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Affiliation(s)
- J M Patricio-Gómez
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del I.P.N., México CdMx, Mexico
| | - R A Valdez
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del I.P.N., México CdMx, Mexico
| | - A Veloz
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del I.P.N., México CdMx, Mexico
| | - L Aguilar-Vega
- Departamento de Microbiología y Parasitología, Facultad de Medicina, UNAM, México CdMx, Mexico
| | - R Zurabian
- Departamento de Microbiología y Parasitología, Facultad de Medicina, UNAM, México CdMx, Mexico
| | - M C Romano
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del I.P.N., México CdMx, Mexico.
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Chávez-Güitrón L, Morales-Montor J, Muñoz-Guzmán M, Nava-Castro K, Ramírez-Álvarez H, Moreno-Méndoza N, Hernández-Cervantes R, Alba-Hurtado F. The in vitro effect of prolactin on the growth, motility and expression of prolactin receptors in larvae of Toxocara canis. Vet Parasitol 2016. [DOI: https://doi.org/10.1016/j.vetpar.2016.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Mhashilkar AS, Vankayala SL, Liu C, Kearns F, Mehrotra P, Tzertzinis G, Palli SR, Woodcock HL, Unnasch TR. Identification of Ecdysone Hormone Receptor Agonists as a Therapeutic Approach for Treating Filarial Infections. PLoS Negl Trop Dis 2016; 10:e0004772. [PMID: 27300294 PMCID: PMC4907521 DOI: 10.1371/journal.pntd.0004772] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/21/2016] [Indexed: 11/27/2022] Open
Abstract
Background A homologue of the ecdysone receptor has previously been identified in human filarial parasites. As the ecdysone receptor is not found in vertebrates, it and the regulatory pathways it controls represent attractive potential chemotherapeutic targets. Methodology/ Principal Findings Administration of 20-hydroxyecdysone to gerbils infected with B. malayi infective larvae disrupted their development to adult stage parasites. A stable mammalian cell line was created incorporating the B. malayi ecdysone receptor ligand-binding domain, its heterodimer partner and a secreted luciferase reporter in HEK293 cells. This was employed to screen a series of ecdysone agonist, identifying seven agonists active at sub-micromolar concentrations. A B. malayi ecdysone receptor ligand-binding domain was developed and used to study the ligand-receptor interactions of these agonists. An excellent correlation between the virtual screening results and the screening assay was observed. Based on both of these approaches, steroidal ecdysone agonists and the diacylhydrazine family of compounds were identified as a fruitful source of potential receptor agonists. In further confirmation of the modeling and screening results, Ponasterone A and Muristerone A, two compounds predicted to be strong ecdysone agonists stimulated expulsion of microfilaria and immature stages from adult parasites. Conclusions The studies validate the potential of the B. malayi ecdysone receptor as a drug target and provide a means to rapidly evaluate compounds for development of a new class of drugs against the human filarial parasites. The human filarial parasites are the causative agents of two neglected tropical diseases targeted for elimination by the international community. The current elimination programs rely upon the mass distribution of a limited number of drugs, leaving the programs open to failure in the event that resistance develops. Thus, there is a critical need for novel chemotherapeutic agents to supplement the current arsenal. The filarial parasites are ecdysozoans, whose developmental processes are controlled by a master regulator, the ecdysone receptor. Here we validate the potential of the filarial ecdysone receptor as a chemotherapeutic target and report the development of high throughput and virtual screening assays that may be used to compounds that target it.
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Affiliation(s)
- Amruta S. Mhashilkar
- Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Sai L. Vankayala
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Canhui Liu
- Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Fiona Kearns
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Priyanka Mehrotra
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - George Tzertzinis
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Subba R. Palli
- Department of Entomology, University of Kentucky, Lexington, Kentucky, United States of America
| | - H. Lee Woodcock
- Department of Chemistry, University of South Florida, Tampa, Florida, United States of America
| | - Thomas R. Unnasch
- Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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The in vitro effect of prolactin on the growth, motility and expression of prolactin receptors in larvae of Toxocara canis. Vet Parasitol 2016; 224:33-38. [PMID: 27270387 DOI: 10.1016/j.vetpar.2016.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/26/2016] [Accepted: 05/02/2016] [Indexed: 02/05/2023]
Abstract
The in vitro effect of prolactin (PRL) on the growth and motility of Toxocara canis larvae was assessed. Additionally, the expression and location of prolactin receptors (PRL-Rs) were determined in the larvae. Larvae of T. canis were incubated with different concentrations of PRL for different periods of time. The stimulated larvae accelerated their enlargement and increased their motility. The mean percentage of PRL-R+ cells in non-stimulated larvae, measured by flow cytometry was 7.3±0.3%. Compared with non-stimulated larvae, the mean fluorescence intensity (p<0.05) increased in larvae incubated with 40ng/mL of PRL for 10 days. A 465-bp length fragment was amplified from larvae gDNA by PCR. The sequence of this fragment showed 99% similarity with the gene fragment that codes for the PRL-R of the domestic dog. A high concentration of PRL-Rs was immune-located in the posterior region of the larval intestine; therefore, the intestinal cells in this region were most likely the targets for this hormone. Based on these results, PRL-Rs were identified in T. canis larvae, and the in vitro stimulation with PRL increased the number of these receptors, accelerated the growth and modified the activity of larvae. All of the above suggest that T. canis larvae are evolutionarily adapted to recognize the PRL of their definitive host and furthermore might explain the reactivation of tissue-arrested larvae during the gestation of bitches, which does not occur in gestating females of other species.
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Romano MC, Jiménez P, Miranda-Brito C, Valdez RA. Parasites and steroid hormones: corticosteroid and sex steroid synthesis, their role in the parasite physiology and development. Front Neurosci 2015; 9:224. [PMID: 26175665 PMCID: PMC4484981 DOI: 10.3389/fnins.2015.00224] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 06/08/2015] [Indexed: 01/09/2023] Open
Abstract
In many cases parasites display highly complex life cycles that include the penetration and permanence of the larva or adults within host organs, but even in those that only have one host, reciprocal, intricate interactions occur. Evidence indicates that steroid hormones have an influence on the development and course of parasitic infections. The host gender's susceptibility to infection, and the related differences in the immune response are good examples of the host-parasite interplay. However, the capacity of these organisms to synthesize their own steroidogenic hormones still has more questions than answers. It is now well-known that many parasites synthesize ecdysteroids, but limited information is available on sex steroid and corticosteroid synthesis. This review intends to summarize some of the existing information in the field. In most, but not all parasitosis the host's hormonal environment determines the susceptibility, the course, and severity of parasite infections. In most cases the infection disturbs the host environment, and activates immune responses that end up affecting the endocrine system. Furthermore, sex steroids and corticosteroids may also directly modify the parasite reproduction and molting. Available information indicates that parasites synthesize some steroid hormones, such as ecdysteroids and sex steroids, and the presence and activity of related enzymes have been demonstrated. More recently, the synthesis of corticosteroid-like compounds has been shown in Taenia solium cysticerci and tapeworms, and in Taenia crassiceps WFU cysticerci. In-depth knowledge of the parasite's endocrine properties will contribute to understand their reproduction and reciprocal interactions with the host, and may also help designing tools to combat the infection in some clinical situations.
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Affiliation(s)
- Marta C Romano
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del IPN Mexico city, Mexico
| | - Pedro Jiménez
- Centro de Investigación en Reproducción Animal, CINVESTAV-UAT Tlaxcala, Mexico
| | - Carolina Miranda-Brito
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del IPN Mexico city, Mexico
| | - Ricardo A Valdez
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del IPN Mexico city, Mexico
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An EcR homolog from the filarial parasite, Dirofilaria immitis requires a ligand-activated partner for transactivation. Mol Biochem Parasitol 2010; 171:55-63. [DOI: 10.1016/j.molbiopara.2010.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/01/2010] [Accepted: 02/02/2010] [Indexed: 11/23/2022]
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Parihar M, Minton RL, Flowers S, Holloway A, Morehead BE, Paille J, Gissendanner CR. The genome of the nematode Pristionchus pacificus encodes putative homologs of RXR/Usp and EcR. Gen Comp Endocrinol 2010; 167:11-7. [PMID: 20152837 DOI: 10.1016/j.ygcen.2010.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 12/20/2009] [Accepted: 02/05/2010] [Indexed: 11/28/2022]
Abstract
Ecdysteroid signaling is an important regulator of arthropod development and reproduction. However, the role of ecdysteroid signaling in another Ecdysozoan animal, the nematode, remains unclear. We report here the identification, cloning, and temporal expression of genes encoding putative homologs of the two nuclear receptor components of the ecdysone receptor, RXR/Usp (NR2B) and EcR (NR1H), in the nematode Pristionchus pacificus. The P. pacificus genes Ppa-pnhr-1 and Ppa-pnhr-2 encode nuclear receptors with strong sequence similarity to RXR/Usp and EcR, respectively. Maximum likelihood analysis incorporating both DNA-binding and ligand-binding domains places the two proteins in the NR2B and NR1H groups with strong bootstrap support. RT-PCR analysis reveals that both Ppa-pnhr-1 and Ppa-pnhr-2 are expressed during larval development and that Ppa-pnhr-1 expression oscillates with the molting cycle. The identification of a putative ecdysone receptor in a nematode amenable to genetic analysis provides a powerful system to investigate the function and evolution of ecdysone receptor signaling in the Nematoda.
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Affiliation(s)
- Manish Parihar
- Department of Biology, University of Louisiana at Monroe, Monroe, LA 71209, USA
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Graham LD, Kotze AC, Fernley RT, Hill RJ. An ortholog of the ecdysone receptor protein (EcR) from the parasitic nematode Haemonchus contortus. Mol Biochem Parasitol 2010; 171:104-7. [PMID: 20226216 DOI: 10.1016/j.molbiopara.2010.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Revised: 03/02/2010] [Accepted: 03/02/2010] [Indexed: 11/30/2022]
Abstract
High concentrations (> or =4.2mM) of 20E inhibit the development of Haemonchus contortus eggs to the L3 larval stage. We report the cloning of cDNA encoding an EcR ortholog (HcEcR) from H. contortus mRNA expressed during L3. Phylogenetically, this and the putative EcR from Brugia malayi form a separate branch between arthropod EcRs and liver X receptors. Two isoforms of HcEcR differ in the inclusion/omission of a 3-residue segment in the A/B domain. Single nucleotide polymorphisms at 49 positions can be grouped into two major patterns in the A/BC segment and two in the DE/F segment. Some 35% of the highly conserved ecdysteroid-contacting residues in insect EcRs are also conserved in the HcEcR ligand binding domain, but it contains unusual residue choices at other ligand-contacting positions. Recombinant co-expression of HcEcR DE/F segments with a phthirapteran USP DE/F segment in insect cells resulted in stable proteins which did not heterodimerize or bind [(3)H]ponasterone A.
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Affiliation(s)
- Lloyd D Graham
- CSIRO Food & Nutritional Sciences, P.O. Box 52, North Ryde, NSW 1670, Australia.
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Molecular evidence for a functional ecdysone signaling system in Brugia malayi. PLoS Negl Trop Dis 2010; 4:e625. [PMID: 20231890 PMCID: PMC2834746 DOI: 10.1371/journal.pntd.0000625] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Accepted: 01/22/2010] [Indexed: 11/20/2022] Open
Abstract
Background Filarial nematodes, including Brugia malayi, the causative agent of lymphatic filariasis, undergo molting in both arthropod and mammalian hosts to complete their life cycles. An understanding of how these parasites cross developmental checkpoints may reveal potential targets for intervention. Pharmacological evidence suggests that ecdysteroids play a role in parasitic nematode molting and fertility although their specific function remains unknown. In insects, ecdysone triggers molting through the activation of the ecdysone receptor: a heterodimer of EcR (ecdysone receptor) and USP (Ultraspiracle). Methods and Findings We report the cloning and characterization of a B. malayi EcR homologue (Bma-EcR). Bma-EcR dimerizes with insect and nematode USP/RXRs and binds to DNA encoding a canonical ecdysone response element (EcRE). In support of the existence of an active ecdysone receptor in Brugia we also cloned a Brugia rxr (retinoid X receptor) homolog (Bma-RXR) and demonstrate that Bma-EcR and Bma-RXR interact to form an active heterodimer using a mammalian two-hybrid activation assay. The Bma-EcR ligand-binding domain (LBD) exhibits ligand-dependent transactivation via a GAL4 fusion protein combined with a chimeric RXR in mammalian cells treated with Ponasterone-A or a synthetic ecdysone agonist. Furthermore, we demonstrate specific up-regulation of reporter gene activity in transgenic B. malayi embryos transfected with a luciferase construct controlled by an EcRE engineered in a B. malayi promoter, in the presence of 20-hydroxy-ecdysone. Conclusions Our study identifies and characterizes the two components (Bma-EcR and Bma-RXR) necessary for constituting a functional ecdysteroid receptor in B. malayi. Importantly, the ligand binding domain of BmaEcR is shown to be capable of responding to ecdysteroid ligands, and conversely, ecdysteroids can activate transcription of genes downstream of an EcRE in live B. malayi embryos. These results together confirm that an ecdysone signaling system operates in B. malayi and strongly suggest that Bma-EcR plays a central role in it. Furthermore, our study proposes that existing compounds targeting the insect ecdysone signaling pathway should be considered as potential pharmacological agents against filarial parasites. Filarial parasites such as Brugia malayi and Onchocerca volvulus are the causative agents of the tropical diseases lymphatic filariasis and onchocerciasis, which infect 150 million people, mainly in Africa and Southeast Asia. Filarial nematodes have a complex life cycle that involves transmission and development within both mammalian and insect hosts. The successful completion of the life cycle includes four molts, two of which are triggered upon transmission from one host to the other, human and mosquito, respectively. Elucidation of the molecular mechanisms involved in the molting processes in filarial nematodes may yield a new set of targets for drug intervention. In insects and other arthropods molting transitions are regulated by the steroid hormone ecdysone that interacts with a specialized hormone receptor composed of two different proteins belonging to the family of nuclear receptors. We have cloned from B. malayi two members of the nuclear receptor family that show many sequence and biochemical properties consistent with the ecdysone receptor of insects. This finding represents the first report of a functional ecdysone receptor homolog in nematodes. We have also established a transgenic hormone induction assay in B. malayi that can be used to discover ecdysone responsive genes and potentially lead to screening assays for active compounds for pharmaceutical development.
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13
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Vacchina P, Valdéz RA, Gómez Y, Revelli S, Romano MC. Steroidogenic capacity of Trypanosoma cruzi trypomastigotes. J Steroid Biochem Mol Biol 2008; 111:282-6. [PMID: 18640275 DOI: 10.1016/j.jsbmb.2008.06.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 06/17/2008] [Accepted: 06/26/2008] [Indexed: 11/25/2022]
Abstract
American Trypanosomiasis is caused by the hemoflagellate Trypanosoma cruzi (T. cruzi) and affects millions of persons causing variable degrees of digestive and heart disturbances. As far as we concerned, T. cruzi capacity to synthesize steroid hormones has not been investigated. Therefore, the aim of this work was to investigate the capacity of T. cruzi trypomastigotes to transform tritiated steroid precursors into androgens and estrogens. The T. cruzi Tulahuén strain was obtained from mice blood. The trypomastigotes were cultured for 6 and 24h in Dulbbeco's modified Eagle's medium plus FCS and antibiotics. Tritiated dehydroepiandrosterone or androstendione were added to the culture media and parasites were incubated for 6 or 24h. The cultures were centrifuged and ether extracted. The steroids were analyzed by thin layer chromatography (TLC) in two solvent systems. After incubation with 3H-androstenedione, T. cruzi trypomastigotes synthesized 3H-testosterone (T), 3H-17beta-estradiol (E2) and 3H-estrone (E1). Metabolism of 3H-DHEA by the parasites yielded 3H-androstendione and 3H-androstendiol at 6h of incubation. The recrystallization procedure further demonstrated the 3H-androstendiol and 3H-17beta-estradiol syntheses. Results indicate for the first time that T. cruzi trypomastigotes produce androgens and estrogens when incubated in the presence of steroid precursors and suggest the presence of active parasite steroidogenic enzymes.
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Affiliation(s)
- P Vacchina
- Instituto de Inmunologia, Facultad de Ciencias Médicas, UNR, Rosario, Argentina
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14
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Fernández Presas AM, Valdez RA, Willms K, Romano MC. The key steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase in Taenia solium and Taenia crassiceps (WFU). Parasitol Res 2008; 103:847-52. [PMID: 18626663 DOI: 10.1007/s00436-008-1066-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Accepted: 05/28/2008] [Indexed: 12/19/2022]
Abstract
Larval and adult stages of Taenia solium and Taenia crassiceps WFU strain were analyzed by histochemical and biochemical methods to determine the existence of steroid pathways. The presence of the key enzyme 3beta-hydroxisteroid-dehydrogenase (3beta-HSD) was examined in frozen sections of cysticerci obtained from mice and segments of tapeworms obtained from the intestine of hamsters. 3beta-HSD activity was detected by nitroblue-tetrazolium products after incubation with dehydroepiandrosterone, androstendiol, or pregnenolone. Tapeworm tissues exhibited 3beta-HSD activity in the subtegumentary areas of the neck and immature proglottids following incubation with androstendiol, as well as surrounding the testes in mature proglottids. T. solium cysticerci exhibited 3beta-HSD activity in the subtegumentary tissues. The synthesis of steroid hormones involving the activity of 3beta-HSD was studied in cysticerci or tapeworms incubated in the presence of tritiated steroid precursors. The culture media were analyzed by thin layer chromatography and showed synthesis of androstendiol, testosterone, and 17beta-estradiol by cysticerci, androstendiol, and 17beta-estradiol by tapeworms. The results strongly suggest the activity of 3beta-HSD in taeniid parasites that have at least a part of the enzymatic chain required for androgen and estrogen synthesis and that the enzymes are present in the larval stage and from the early strobilar stages to the mature proglottids.
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15
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Höss S, Weltje L. Endocrine disruption in nematodes: effects and mechanisms. ECOTOXICOLOGY (LONDON, ENGLAND) 2007; 16:15-28. [PMID: 17219088 DOI: 10.1007/s10646-006-0108-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
This paper reviews the current knowledge on endocrine disruption in nematodes. These organisms have received little attention in the field of ecotoxicology, in spite of their important role in aquatic ecosystems. Research on endocrine regulation and disruption in nematodes, especially the more recent studies, concentrate mainly on one species, Caenorhabditis elegans. Although an endocrine system is not known in nematodes, there is evidence that many processes are regulated via hormonal pathways. As vertebrate hormones, such as steroids, may have endocrine functions in nematodes as well, endocrine disrupting chemicals (EDCs) defined for vertebrates may also be able to influence nematodes. The studies that are reviewed here, and own data showed that potential EDCs can affect nematodes on all organizational levels, from molecules to communities. It is concluded that nematodes, notably its prominent species C. elegans, are a promising organism group for the development of biomonitoring tools, provided that more mechanistic evidence is gathered on hormonal processes within these animals.
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16
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Valdéz RA, Jiménez P, Cartas AL, Gómez Y, Romano MC. Taenia solium cysticerci synthesize androgens and estrogens in vitro. Parasitol Res 2006; 98:472-6. [PMID: 16416116 DOI: 10.1007/s00436-005-0095-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2005] [Accepted: 11/16/2005] [Indexed: 11/30/2022]
Abstract
Cysticerci from Taenia solium develop in the pig muscle and cause severe diseases in humans. Here we report on the capacity of T. solium cysticerci to synthesize sex steroid hormones. T. solium cysticerci were dissected from infected pork meat. Parasites were incubated for different periods in culture media plus antibiotics and tritiated steroid precursors. Blanks and parasite culture media were extracted and analyzed by thin-layer chromatography (TLC) in two different solvent systems. In some experiments, the scoleces were incubated separately. Results showed that T. solium cysticerci transform [(3)H]androstenedione to [(3)H]testosterone in a time-dependent manner. The production was confirmed in two different solvent systems. The incubation with [(3)H]testosterone yielded only small amounts of [(3)H]androstenedione. The recrystallization procedure further demonstrated that the metabolite identified by TLC was testosterone. The isolated scoleces incubated in the presence of [(3)H]androstenedione yielded [(3)H]testosterone and small quantities of [(3)H]17beta-estradiol. The results reported here demonstrate that T. solium cysticerci have the capacity to synthesize steroid hormones.
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Affiliation(s)
- R A Valdéz
- Departamento de Fisiología, Biofísica y NC, CINVESTAV, 14-740, 07000, México, DF, México
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17
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Soriano IR, Riley IT, Potter MJ, Bowers WS. Phytoecdysteroids: a novel defense against plant-parasitic nematodes. J Chem Ecol 2005; 30:1885-99. [PMID: 15609826 DOI: 10.1023/b:joec.0000045584.56515.11] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The phytoecdysteroid, 20-hydroxyecdysone (20E), is a major molting hormone of invertebrates, possibly including nematodes. As 20E is inducible in spinach, the defensive role against plant-parasitic nematodes was investigated. The effects of direct application on nematodes was assessed by treating cereal cyst nematode, Heterodera avenae, juveniles with concentrations of 20E from 8.2 x 10(-8) to 5.2 x 10(-5) M before applying to Triticum aestivum growing in sand. H. avenae, Heterodera schachtii (sugarbeet cyst nematode), Meloidogyne javanica (root-knot nematode), and Pratylenchus neglectus (root lesion nematode) were treated with 5.2 x 10(-5) 20E and incubated in moist sand. To test the protective effects of 20E in plants, the latter three nematodes were applied to Spinacia oleracea in which elevated concentrations of 20E had been induced by methyl jasmonate. Abnormal molting, immobility, reduced invasion, impaired development, and death occurred in nematodes exposed to 20E either directly at concentration above 4.2 x 10(-7) M or in plants. Phytoecdysteroid was found to protect spinach from plant-parasitic nematodes and may confer a mechanism for nematode resistance.
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Affiliation(s)
- Imelda R Soriano
- Plant and Pest Science, School of Agriculture and Wine, University of Adelaide, PMB1 Glen Osmond, SA 5064, Australia.
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18
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Yarim M, Yildiz K, Kabakci N, Karahan S. Immunohistochemical localisation of 3beta-hydroxysteroid dehydrogenase in Sarcocystis spp. Parasitol Res 2004; 93:457-60. [PMID: 15243798 DOI: 10.1007/s00436-004-1152-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Accepted: 06/08/2004] [Indexed: 10/26/2022]
Abstract
3Beta-hydroxysteroid-dehydrogenase (3beta-HSD) is an isoenzyme that catalyses an essential step in the synthesis of all classes of active steroid hormones. The presence of steroid hormones of the vertebrate type in invertebrates is acknowledged in addition to a group of steroid-like hormones called ecdysteroids that were present in arthropods and helminths. In the present study, 3beta-HSD was detected in the bradyzoites enclosed in sarcocysts of Sarcocystis spp. with immunohistochemistry. The results suggest that self-originating steroid hormones may play important roles in the development of Sarcocystis spp., and possibly in the regulation of the reciprocal immune interaction between the host and these parasites.
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Affiliation(s)
- Murat Yarim
- Department of Pathology, Faculty of Veterinary Medicine, University of Kirikkale, Yahsihan, Turkey.
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19
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Gissendanner CR, Crossgrove K, Kraus KA, Maina CV, Sluder AE. Expression and function of conserved nuclear receptor genes in Caenorhabditis elegans. Dev Biol 2004; 266:399-416. [PMID: 14738886 DOI: 10.1016/j.ydbio.2003.10.014] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Caenorhabditis elegans genome encodes 284 nuclear receptor (NR) genes. Among these 284 NR genes are 15 genes conserved among the Metazoa. Here, we analyze the expression and function of eight heretofore uncharacterized conserved C. elegans NR genes. Reporter gene analysis demonstrates that these genes have distinct expression patterns and that a majority of the C. elegans cell types express a conserved NR gene. RNA interference with NR gene function resulted in visible phenotypes for three of the genes, revealing functions in various processes during postembryonic development. Five of the conserved NR genes are orthologs of NR genes that function during molting and metamorphosis in insects. Functional studies confirm a role for most of these 'ecdysone cascade' NR orthologs during the continuous growth and dauer molts. Transcript levels for these genes fluctuate in a reiterated pattern during the molting cycles, reminiscent of the expression hierarchy observed in the insect ecdysone response. Together, these analyses provide a foundation for further dissecting the role of NRs in nematode development as well as for evaluating conservation of NR functions among the Metazoa.
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20
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Romano MC, Valdéz RA, Cartas AL, Gómez Y, Larralde C. Steroid hormone production by parasites: the case of Taenia crassiceps and Taenia solium cysticerci. J Steroid Biochem Mol Biol 2003; 85:221-5. [PMID: 12943707 DOI: 10.1016/s0960-0760(03)00233-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Many examples of reciprocal endocrine interactions between parasites and hosts have been found in insects, arthropods and mammals. Cysticercosis produced by Taenia solium metacestodes is a widely distributed parasite infection that affects the human and the pig. Taenia crassiceps experimental murine cysticercosis has been used to explore the role of biological factors involved in host-parasite interactions. We had shown that T. crassiceps cysticercosis affects the serum concentration of steroid hormones and the reproduction behavior of the male mice host. In an effort to understand the biology of the parasite, we had investigated the parasite capacity to produce sex steroids. For this purpose, T. crassiceps cysticerci were incubated in the presence of different steroid precursors. TLC and recrystallization procedures showed that testosterone is produced from 3H-androstenedione in cysticerci. The conversion of 3H-testosterone to androstenedione, although present is much less significant. In addition, we had studied the production of testosterone by T. solium cysticerci. For this purpose, cysticerci were dissected from pork meat and incubated as above described. The results showed that T. solium cysticerci also produce testosterone. We have speculated about the importance of androgens in the growth of T. crassiceps cysticerci and found that the addition of the antiandrogen flutamide to the culture media of the parasites significantly decreased 3H-thymidine incorporation. We therefore hypothesized, that the ability of cysticerci to produce testosterone from steroid precursors might be important for the parasite growth and development.
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Affiliation(s)
- M C Romano
- Departamento de Fisiología, Biofísica y Neurociencias, CINVESTAV del IPN, Apdo. Postal 14-740, 07000 D.F., Mexico, Mexico.
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21
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Noriega R, Ramberg FB, Hagedorn HH. Ecdysteroids and oocyte development in the black fly Simulium vittatum. BMC DEVELOPMENTAL BIOLOGY 2002; 2:6. [PMID: 12015816 PMCID: PMC111195 DOI: 10.1186/1471-213x-2-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2002] [Accepted: 04/24/2002] [Indexed: 11/10/2022]
Abstract
BACKGROUND Oocyte development was studied in the autogenous black fly, Simulium vittatum (Diptera, Nematocera), a vector of Onchocerca volvulus, the causative agent of onchocerciasis. RESULTS Oocyte growth was nearly linear between adult eclosion and was complete by 72 hours at 21 degrees C. The oocyte became opaque at 14 hours after eclosion indicating the initiation of protein yolk deposition. The accumulation of vitellogenin was measured using SDS-PAGE. The density of the yolk protein bands at about 200 and 65 kDa increased during the first and second days after eclosion. The amount of protein in the 200 kDa band of vitellogenin, determined using densitometry, rapidly increased between 12 and 25 hours after eclosion. Ecdysteroid levels were measured using a competitive ELISA. Ecdysteroid levels increased rapidly and subsequently declined during the first day after eclosion. CONCLUSION These data show a correlation between the appearance of vitellogenin in the oocyte, and the rise in ecdysteroids. A possible relationship to molting of the nematode, Onchocerca volvulus, is discussed.
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Affiliation(s)
- Rafael Noriega
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15216, USA
| | - Frank B Ramberg
- Department of Entomology and Center for Insect Science University of Arizona, Tucson, AZ, USA
| | - Henry H Hagedorn
- Department of Entomology and Center for Insect Science University of Arizona, Tucson, AZ, USA
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22
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Gagliardo LF, McVay CS, Appleton JA. Molting, ecdysis, and reproduction of Trichinella spiralis are supported in vitro by intestinal epithelial cells. Infect Immun 2002; 70:1853-9. [PMID: 11895947 PMCID: PMC127886 DOI: 10.1128/iai.70.4.1853-1859.2002] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trichinella spiralis is an obligate parasite of animals that has an unusual intracellular life cycle. Investigation of parasitism at the cellular and molecular levels has been challenging because of a shortage of tools for in vitro cultivation of T. spiralis. We have found that T. spiralis larvae molt, ecdyse, develop to adulthood, and reproduce when they are inoculated onto cultured intestinal epithelial cells. Initially, larvae invade and migrate through cells in a monolayer (T. ManWarren, L. Gagliardo, J. Geyer, C. McVay, S. Pearce-Kelling, and J. Appleton, Infect. Immun. 65:4806-4812, 1997). During prolonged culture in Caco-2 epithelial cells, L1 larvae molted and ecdysed with efficiencies as high as 50%. Molting and ecdysis in vitro required entry of the parasite into cells; conditions that prevented entry into cells also prevented ecdysis. When larvae were inoculated at a low density and cultured for 5 to 9 days, as many as 50% of the larvae developed to adult stages. Low numbers of mature male worms with copulatory appendages were observed in these cultures. The majority of worms that survived for five or more days were unfertilized females. Low-density cultures supported development of female worms with embryos at rates of 4 to 5%. These results show that the intestinal life cycle of T. spiralis can be supported entirely by host epithelial cells. Our model should allow more detailed investigation of intracellular parasitism by T. spiralis.
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Affiliation(s)
- L F Gagliardo
- James A. Baker Institute for Animal Health, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
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Rhoads ML, Fetterer RH, Urban JF. Cuticular collagen synthesis by Ascaris suum during development from the third to fourth larval stage: identification of a potential chemotherapeutic agent with a novel mechanism of action. J Parasitol 2001; 87:1144-9. [PMID: 11695381 DOI: 10.1645/0022-3395(2001)087[1144:ccsbas]2.0.co;2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The dominant proteins released by Ascaris suum during development in vitro from the L3 to L4 stage were identified as collagenous cuticular proteins by sequence analysis and susceptibility to digestion by collagenase. Under reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the collagen proteins separated into 3 groups with molecular weights estimated at 32 kDa, 54-60 kDa, and 71-91 kDa. The 32-kDa protein represents monomeric collagen; the 54-60- and 71-91-kDa components represent dimeric and trimeric forms, respectively, polymerized by nonreducible cross-links. Furthermore, the release of these forms of collagen was developmentally regulated, as exemplified by a sequential temporal progression from monomeric to dimeric to trimeric forms in association with the in vitro transition from L3 to L4. The data suggest that collagen released in vitro during development of A. suum L3 to L4 reflects the increased translation of collagen gene products and their initial assembly into higher molecular weight molecules associated with the synthesis of the L4 cuticle. A biotinylated dipeptidyl fluoromethylketone cysteine protease inhibitor (Bio-phe-ala-FMK) bound specifically to the 32-kDa collagen and, to a lesser extent, to a 30-kDa protein; binding was dependent on the presence of dithiothreitol (DTT) and was prevented by iodoacetamide. Because cysteine residues play an essential role in the initial assembly of the collagen monomers into the higher molecular weight oligomers present in the mature nematode cuticle, inhibition of molting of A. suum L3 to L4 by the cysteine protease inhibitor Z-phe-ala-FMK might be due to its binding to thiol groups of collagen monomers during a critical phase of collagen assembly. Prevention of cystine cross-links during this critical period of cuticle assembly by peptide-FMK inhibitors may represent a potential control mechanism having a novel mechanism of action.
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Affiliation(s)
- M L Rhoads
- Parasite Biology, Epidemiology, and Systematics Laboratory, Animal and Natural Resources Institute, United States Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705, USA.
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24
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Fetterer RH. Growth and cuticular synthesis in Ascaris suum larvae during development from third to fourth stage in vitro. Vet Parasitol 1996; 65:275-82. [PMID: 8983153 DOI: 10.1016/s0304-4017(96)00956-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Growth, molting and cuticular protein synthesis were determined during the development of Ascaris suum grown in vitro from the third (L3) to the fourth (L4) larval stage. The larvae remained highly viable (90%) and 70% reached the L4 by 7 days in culture (DIC). Analysis of growth and development indicated that ecdysis was asynchronous. The synthesis of noncuticular and cuticular proteins was monitored using 35S-methionine as a metabolic label. Synthesis of noncuticular, cuticular and collagenous cuticular proteins increased in a constant manner, reaching maximal values at about 6 DIC. Synthesis of noncollagenous cuticular proteins (cuticlin) remained relatively constant during most of the culture period, but increased from 6 to 7 DIC. The increase in cuticlin synthesis and the corresponding decrease in cuticular collagen synthesis noted at 7 DIC might represent the synthesis of the outer portions of the adult cuticle in preparation for the fourth molt. The results of this study suggest that this in vitro development system for A. suum, while not suitable to study events regulating the precise timing of molting and cuticular synthesis, might be useful for the analysis of potential growth regulators.
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Affiliation(s)
- R H Fetterer
- United States Department of Agriculture, Beltsville Agricultural Research Center, MD 20740, USA
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25
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Yates RA, Tuan RS, Shepley KJ, Unnasch TR. Characterization of genes encoding members of the nuclear hormone receptor superfamily from Onchocerca volvulus. Mol Biochem Parasitol 1995; 70:19-31. [PMID: 7637701 DOI: 10.1016/0166-6851(95)00018-v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Several lines of evidence suggest that molting in parasitic nematodes is controlled through the action of steroid molting hormones, or ecdysones. In other organisms, the central mediator of steroid hormone action is the hormone receptor. These receptor molecules are members of a superfamily of proteins called the nuclear hormone receptor family. Using an oligonucleotide derived from the amino-acid sequence of the Drosophila melanogaster ecdysone receptor, genes encoding homologues of the nuclear hormone receptor family were identified in the genome of the human filarial parasite Onchocerca volvulus. The O. volvulus genome contains at least three genes that encode putative members of the nuclear hormone receptor superfamily. A complete cDNA for one of these genes, designated OvNHR-1, has been isolated and characterized. The OvNHR-1 cDNA was 2378 bp in length, and contained a single open reading frame of 1104 bp. The open reading frame encoded a peptide with all of the features characteristic of a member of the nuclear hormone receptor superfamily of proteins. OVNHR-1 appeared to be encoded by a single-copy gene. Expression of the mRNA corresponding to OvNHR-1 was developmentally regulated, with maximal expression occurring during early embryogenesis. The polypeptide encoded by the OvNHR-1 open reading frame is antigenic in a minority of individuals exposed to O. volvulus.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Helminth/biosynthesis
- Antigens, Helminth/genetics
- Antigens, Helminth/immunology
- Base Sequence
- Cell Nucleus/metabolism
- Cloning, Molecular
- DNA, Complementary/genetics
- Ecdysone/metabolism
- Escherichia coli
- Female
- Gene Expression Regulation, Developmental
- Genes, Helminth
- Helminth Proteins/biosynthesis
- Helminth Proteins/genetics
- Helminth Proteins/immunology
- In Situ Hybridization
- Molecular Sequence Data
- Multigene Family
- Onchocerca volvulus/embryology
- Onchocerca volvulus/genetics
- Onchocerca volvulus/growth & development
- Onchocerca volvulus/immunology
- Open Reading Frames
- Phylogeny
- Receptors, Cytoplasmic and Nuclear/biosynthesis
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/immunology
- Receptors, Steroid/biosynthesis
- Receptors, Steroid/genetics
- Receptors, Steroid/immunology
- Recombinant Fusion Proteins/biosynthesis
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Affiliation(s)
- R A Yates
- Division of Geographic Medicine, University of Alabama at Birmingham 35294, USA
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26
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Davies KA, Fisher JM. On hormonal control of moulting in Aphelenchus avenae (Nematoda: Aphelenchida). Int J Parasitol 1994; 24:649-55. [PMID: 7928066 DOI: 10.1016/0020-7519(94)90117-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Ligatures applied to juveniles of A. avenae at particular developmental times and positions limited the moult to the anterior or posterior portion of the nematode. To partition the moult, ligatures needed to be applied from about 4 h after receipt of the stimulus for moulting up till the onset of lethargus. Nematodes which were ligated before the stimulus failed to moult, while nematodes which were ligated after the onset of lethargus moulted on both sides of the ligature. If, at the appropriate time, ligatures were placed in the anterior third of the nematode, then the posterior portion of the nematode moulted; if the ligatures were placed in the posterior half, then the anterior portion of the nematode moulted. If the ligatures were placed between third and half the length of the nematode, then either the anterior or posterior portion moulted, or moulting was prevented. Extracts of lyophilised samples of mixed populations of A. avenae induced about 20% pupation in Musca domestica bioassays giving a weight of 80-320 ng ecdysteroid/g dry weight of nematodes. Externally applied 20-OH ecdysone at 2 x 10(-3) M stimulated moulting in the non-moulted portion of ligated nematodes but 2 x 10(-7) M did not.
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Affiliation(s)
- K A Davies
- Department of Crop Protection, Waite Agricultural Research Institute, University of Adelaide, South Australia
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Nembo B, Duie P, Garcia M, Breton P, Gayral P, Porcheron P, Goudey-Perriere F. Levels of ecdysteroid-like material in adults of Nippostrongylus brasiliensis during the intestinal phase. J Helminthol 1993; 67:305-15. [PMID: 8132976 DOI: 10.1017/s0022149x00013316] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Total ecdysteroid-like immunoreactive material was assayed and quantified in adults of the parasitic nematode N. brasiliensis during the intestinal phase in the rat in order to detect possible physiological fluctuations in titre. Worms of the same sex isolated from one rat were pooled in order to quantify ecdysteroids using enzyme immunoassay (EIA). The concentration of ecdysteroids fluctuated during adult life according to the sex and the age of the parasite. Important differences of levels of ecdysteroid-like compounds between the two sexes of parasites were noted particularly at 128 and 168 h post-infection. The peak at 128 h, present in female, but not in male worms, corresponds to the time of egg-laying. Following HPLC-EIA analysis, the presence of ecdysone, 20-hydroxyecdysone and apolar ecdysteroid-like material was ascertained during this peak. The physiological role and the possible origin of ecdysteroids in this nematode are discussed.
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Affiliation(s)
- B Nembo
- Laboratoire de Biologie et Contrôle des Organismes Parasites, Faculté de Pharmacie, Châtenay-Malabry, France
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Fleming MW. Ecdysteroids during development in the ovine parasitic nematode, Haemonchus contortus. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1993; 104:653-5. [PMID: 8472534 DOI: 10.1016/0305-0491(93)90192-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
1. Samples of embryonating eggs, infective larvae, fourth-stage larvae, young adults, and male and female mature adults of Haemonchus contortus were collected for steroids analysis; lipids were extracted, partially purified, fractionated with HPLC, and analyzed for ecdysteroids by radioimmunoassay. 2. Free ecdysone and 20-hydroxyecdysone were detected in all samples; maximal concentrations occurred in the fourth-stage larvae and young adults. 3. Conjugated ecdysone and 20-hydroxyecdysone were detected in all samples but the infected larvae; maximal concentrations occurred in the fourth-stage larvae and young adults. 4. Patterns of ecdysteroid occurrence support regulatory roles in embryogenesis, cuticular deposition, and gonadogenesis. 5. Relative concentrations of ecdysteroids are comparable to those previously reported in eggs and adults of Ascaris suum.
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Affiliation(s)
- M W Fleming
- Helminthic Diseases Laboratory, Livestock and Poultry Sciences Institute, U.S. Department of Agriculture, Beltsville, MD 20705
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Goudey-Perriere F, Simo BF, Maccario J, Perriere C, Gayral P. Effects of ecdysteroids on reproductive physiology of Nippostrongylus brasiliensis (Nematoda) in vivo. ACTA ACUST UNITED AC 1993; 103:105-9. [PMID: 1360363 DOI: 10.1016/0742-8413(92)90236-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
1. The influence of ecdysteroids (ecdysone and ecdysterone) was investigated on the control of reproduction in the parasitic nematode Nippostrongylus brasiliensis in vivo. 2. Infestive larvae (L3) were immersed in solutions of ecdysteroids (2.2 microM) at 37 degrees C for 4 hr before injection into the host. The effect on egg-laying was observed two stages later. 3. The treatment increased egg-laying, but had no influence on the timing of the reproductive period. The greatest effect was observed with ecdysone, ecdysterone only inducing a small and non-significant stimulation under our experimental conditions. 4. The physiological role of ecdysteroids in meiosis and gonadal development in nematodes is discussed.
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Affiliation(s)
- F Goudey-Perriere
- Laboratoire de Biologie et Contrôle des Organsimes parasites, Faculté de Pharmacie de l'Université de Paris Sud, France
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Behnke JM, Barnard CJ, Wakelin D. Understanding chronic nematode infections: evolutionary considerations, current hypotheses and the way forward. Int J Parasitol 1992; 22:861-907. [PMID: 1459783 DOI: 10.1016/0020-7519(92)90046-n] [Citation(s) in RCA: 152] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- J M Behnke
- Department of Life Science, University of Nottingham, University Park, U.K
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O'Hanlon GM, Cleator M, Mercer JG, Howells RE, Rees HH. Metabolism and fate of ecdysteroids in the nematodes Ascaris suum and Parascaris equorum. Mol Biochem Parasitol 1991; 47:179-87. [PMID: 1944416 DOI: 10.1016/0166-6851(91)90177-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
When injected with [3H]ecdysone and maintained in vitro, the parasitic nematodes, Ascaris suum and Parascaris equorum each produced a series of polar and relatively apolar metabolites. A. suum metabolised the compound into ecdysonoic acid ([3H]EOIC), ecdysone 25-glucoside ([3H]E25gluc), putative ecdysone 22-phosphate ([3H]E22P) and a series of at least six relatively apolar metabolites. All of these, except ecdysonoic acid, were hydrolysed by a crude enzyme preparation from Helix pomatia, releasing ecdysone. In a similar study, P. equorum produced ecdysone 25-glucoside, putative ecdysone 22-phosphate and a series of relatively apolar compounds all of which were hydrolysed by H. pomatia enzymes, releasing ecdysone. [3H]Ecdysone 25-glucoside was the most abundant single metabolite in both species, and in P. equorum, at least, was released into the culture medium in relatively large amounts. Apolar metabolites were present in worm samples and were the major, if not the only radiolabelled compounds detected in eggs of both species. Data indicated a metabolic relationship between some of the apolar conjugates found in both nematode species and ecdysone 25-glucoside.
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Affiliation(s)
- G M O'Hanlon
- Department of Biochemistry, University of Liverpool, U.K
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Lawrence PO. Hormonal effects on insects and other endoparasites in vitro. IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY : JOURNAL OF THE TISSUE CULTURE ASSOCIATION 1991; 27A:487-96. [PMID: 1869491 DOI: 10.1007/bf02631150] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Metamorphic and reproductive events in vertebrates and invertebrates are under endocrine control and are often correlated with developmental, behavioral, or reproductive changes in the parasites living in or on these hosts. This paper reviews selected examples of a) host hormone mediated influences on endoparasites in vivo, b) host hormone effects in vitro on protozoan, helminth, and insect endoparasites, and c) identifies possible relationships in hormone effects across parasite taxa. The significance of studies on endoparasites in vitro in relation to the impact of host hormones, antihelminthic, and prophylactic drugs on parasite growth and proliferation will also be addressed. A review of the literature indicates only limited studies have been done in vitro in an attempt to elucidate the bases of reported host hormone influences on endoparasites in vivo. Steroid hormones of hosts seem to stimulate growth, molting or encystment or both of helminth, insect, and protozoan parasites. Vertebrate steroids such as estrogen, testosterone, and progesterone had primarily reproduction- or growth-promoting effects or both on protozoan and nematode parasites. Insect ecdysteroids such as ecdysone, 20-hydroxyecdysone, and makisterone were the most widely studied steroids in vitro and induced growth or molting or both of cestode, nematode, and insect parasite larvae. Although juvenile hormone (JH III) stimulated growth in the protozoan and nematode parasites tested, the analogue methoprene and JH precursors, farnesal, farnesol, and farnesol methyl ether had various effects. Biogenic amines also varied in their effects on the nematode parasites tested, while the peptide hormone, insulin, stimulated growth in the protozoans tested. The evidence for in vitro effects of host hormones on their natural endoparasites is patchy at best. Additional studies are needed to identify the biochemical bases for the numerous host hormone mediated effects on parasites.
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Affiliation(s)
- P O Lawrence
- Department of Zoology, University of Florida, Gainesville 32611
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Fetterer RH, Fleming MW. Effects of plumbagin on development of the parasitic nematodes Haemonchus contortus and Ascaris suum. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY 1991; 100:539-42. [PMID: 1687553 DOI: 10.1016/0742-8413(91)90036-s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Plumbagin (5-hydroxy,2-methyl-1,4-napthoquinone) inhibited the motility and survival of Haemonchus contortus first-stage larvae (L1) with an ED50 of 1 microgram/ml, but was less effective in preventing the development of H. contortus to infective third-stage larvae in a faecal slurry assay. 2. Of the structural analogs tested, plumbagin was the most potent in preventing development of L1 followed in decreasing order of potency by 1,4-naphthoquinone, 5-hydroxy-1,4-napthoquinone (juglone) and 1,2-napthoquinone. 3. Plumbagin had a biphasic effect on development of the fourth-stage Ascaris suum larvae that caused an increase in growth at low concentrations but was lethal at higher doses. 4. Plumbagin and 1,2-napthoquinone partially inhibited embryonation of A. suum eggs.
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Affiliation(s)
- R H Fetterer
- Helminthic Diseases Laboratory, Livestock and Poultry Sciences Institute, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705
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O'Hanlon GM, Mercer JG, Rees HH. Evidence for the release of 20-hydroxyecdysone 25-glucoside by adult female Parascaris equorum (Nematoda) in vitro. Parasitol Res 1991; 77:271-2. [PMID: 2047376 DOI: 10.1007/bf00930872] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- G M O'Hanlon
- Department of Biochemistry, University of Liverpool, UK
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Abstract
The occurrence of ecdysteroids (insect moulting hormones) in nematodes, albeit at low concentrations, has been firmly established. In addition to apparently stimulating moulting in a few species, exogenously applied ecdysteroids have now been shown to have interesting biological effects on meiotic reinitiation in oocytes and on microfilarial production in filariae. Although such effects demonstrate the feasibility of influencing nematode physiology with exogenously applied ecdysteroids, hitherto it has not been possible to demonstrate synthesis de novo of these steroids in nematodes. Thus, it remains to be established whether ecdysteroids are truly endogenous nematode hormones or merely represent compounds with strong biological activity. Nonetheless, there are indications that interference with the ecdysteroid system might be exploitable in the development of novel approaches to control of nematodes.
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Affiliation(s)
- G C Barker
- Department of Pure and Applied Biology, Imperial College, Prince Consort Road, London SW11 2BB, UK
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Baswaïd S, Gharib B, Doumbo O, Quilici M, de Reggi M. Ecdysteroids in urine of African patients infected with helminths. Acta Trop 1990; 47:197-204. [PMID: 1973020 DOI: 10.1016/0001-706x(90)90009-o] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The insect molting hormone and related compounds (ecdysteroids) have been found in patients infected with helminths. To investigate this phenomenon, we quantified and analyzed the urinary ecdysteroids in Malian subjects suffering from various helminthiases, as well as in Europeans. Very high titers (up to 100 nM) were found in some patients, whereas healthy persons had a basic level of 4 nM only. The high RIA activity was mainly due to two compounds. One of them was remarkable for being present in all the positive samples; it comigrated with the 20-hydroxyecdysone standard, both in HPLC and in TLC. The origin and the physiological significance of these compounds are questionable, since there was no clear relationship between their levels and the severity of the diseases. Numerous patients who were heavily infected had normal titers. Nevertheless, there is no doubt that high concentrations of ecdysteroid-like compounds in human urine indicate a pathological condition.
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Affiliation(s)
- S Baswaïd
- Laboratoire de Parasitologie, Marseille, France
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Mercer JG, Barker GC, Howells RE, Rees HH. Investigation of ecdysteroid excretion by adult Dirofilaria immitis and Brugia pahangi. Mol Biochem Parasitol 1990; 38:89-95. [PMID: 2320053 DOI: 10.1016/0166-6851(90)90208-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The excretion of ecdysteroids by the filarial nematode species, Dirofilaria immitis and Brugia pahangi, was examined both in vitro, by the analysis of culture medium, and in vivo, through analysis of serum samples from experimentally infected hosts. There was no evidence of ecdysteroid excretion by intact parasites of either species in vitro. Free ecdysteroids were detected in the serum of ferrets and dogs infected with D. immitis, but concentrations would be at or below the limit of detection in sub-millilitre serum samples. The detection of ecdysteroids in the serum of potential hosts is unlikely to be of value in the diagnosis of filarial infections due to a combination of low titre in the presence of current infection and measurable titre in its absence. Ecdysteroids of dietary origin may contribute to the latter.
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Affiliation(s)
- J G Mercer
- Department of Biochemistry, University of Liverpool, U.K
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Fleming MW. Hormonal Effects on thein vitroLarval Growth of the Swine Intestinal Roundworm,Ascaris suum. ACTA ACUST UNITED AC 1988. [DOI: 10.1080/01688170.1988.10510374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Lafont R, Girault JP, Kerb U. Excretion and metabolism of injected ecdysone in the white mouse. Biochem Pharmacol 1988; 37:1174-7. [PMID: 3355591 DOI: 10.1016/0006-2952(88)90529-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- R Lafont
- Ecole Normale Supérieure, Laboratoire de Biochimie et Physiologie du Développement, C.N.R.S. U.A. 686, Paris, France
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Mercer JG, Munn AE, Rees HH. Caenorhabditis elegans: occurrence and metabolism of ecdysteroids in adults and dauer larvae. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1988; 90:261-7. [PMID: 3409656 DOI: 10.1016/0305-0491(88)90070-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
1. Ecdysteroids were detected in extracts of egg-producing adult Caenorhabditis elegans, in dauer larvae and in dietary bacteria. 2. Similar concentrations of free ecdysteroids were recorded in adults and larvae, although the two life cycle stages differed in their ratio of ecdysone: 20-hydroxyecdysone. 3. Patent adults metabolized [3H]ecdysone into apolar products and putative [3H]ecdysone 22-phosphate.
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Affiliation(s)
- J G Mercer
- Department of Biochemistry, University of Liverpool, UK
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O'Hanlon GM, Howarth OW, Rees HH. Identification of ecdysone 25-O-beta-D-glucopyranoside as a new metabolite of ecdysone in the nematode Parascaris equorum. Biochem J 1987; 248:305-7. [PMID: 3435447 PMCID: PMC1148538 DOI: 10.1042/bj2480305] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A major metabolite of [3H]ecdysone injected into adults of the nematode Parascaris equorum maintained in vitro for 48 h was secreted into the culture medium. The compound could be hydrolysed with a crude hydrolase preparation from Helix pomatia, yielding ecdysone. Sufficient quantity of this material for identification was produced by administration of ecdysone to the parasites. The resulting compound was purified by h.p.l.c. and identified as ecdysone 25-O-beta-D-glucopyranoside by n.m.r. spectroscopy and by fast atom bombardment mass spectrometry of the conjugate and of the sugar released by enzymic hydrolysis. The significance of formation of the glucoside is uncertain.
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Affiliation(s)
- G M O'Hanlon
- Department of Biochemistry, University of Liverpool, U.K
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Fleming MW. Ecdysteroids during embryonation of eggs of Ascaris suum. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. A, COMPARATIVE PHYSIOLOGY 1987; 87:803-5. [PMID: 2887364 DOI: 10.1016/0300-9629(87)90404-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
1. The optimal temperature for in vitro development of fertilized eggs of Ascaris suum was 24 degrees C. 2. Samples (2 X 10(7) eggs) were obtained from in vitro embryonating cultures every 3 days for 4 weeks; lipids were extracted, partially purified, fractionated with HPLC and analyzed for ecdysteroids by radioimmunoassay. 3. Free ecdysone and 20-hydroxyecdysone (20-HE) were at low levels (less than 20 pg) in freshly excised eggs and rose to maximal values on day 6 of embryonation. 4. Conjugated ecdysone and conjugated 20-HE rose to maximal values on day 9. 5. Both free and conjugated ecdysteroids were undetectable from days 15 to 27 of cultivation. 6. These profiles indicate that ecdysteroids might have a selective role in nematode embryonation and/or tanning of the egg shell.
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Affiliation(s)
- J C Comley
- Department of Biochemical Microbiology, The Wellcome Research Laboratories, Beckenham, Kent BR3 3BS, UK
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