Hc-daf-2 encodes an insulin-like receptor kinase in the barber's pole worm, Haemonchus contortus, and restores partial dauer regulation
- Li, Facai, Lok, James, Gasser, Robin, Korhonen, Pasi, Sandeman, Mark, Shi, Deshi, Zhou, Rui, Li, Xiangrui, Zhou, Yanqin, Zhao, Junlong, Hu, Min
- Authors: Li, Facai , Lok, James , Gasser, Robin , Korhonen, Pasi , Sandeman, Mark , Shi, Deshi , Zhou, Rui , Li, Xiangrui , Zhou, Yanqin , Zhao, Junlong , Hu, Min
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal for Parasitology Vol. 44, no. 7 (2014), p. 485-496
- Full Text:
- Reviewed:
- Description: Infective L3s (iL3s) of parasitic nematodes share common behavioural, morphological and developmental characteristics with the developmentally arrested (dauer) larvae of the free-living nematode Caenorhabditis elegans. It is proposed that similar molecular mechanisms regulate entry into or exit from the dauer stage in C. elegans, and the transition from free-living to parasitic forms of parasitic nematodes. In C. elegans, one of the key factors regulating the dauer transition is the insulin-like receptor (designated Ce-DAF-2) encoded by the gene Ce-daf-2. However, nothing is known about DAF-2 homologues in most parasitic nematodes. Here, using a PCR-based approach, we identified and characterised a gene (Hc-daf-2) and its inferred product (Hc-DAF-2) in Haemonchus contortus (a socioeconomically important parasitic nematode of ruminants). The sequence of Hc-DAF-2 displays significant sequence homology to insulin receptors (IR) in both vertebrates and invertebrates, and contains conserved structural domains. A sequence encoding an important proteolytic motif (RKRR) identified in the predicted peptide sequence of Hc-DAF-2 is consistent with that of the human IR, suggesting that it is involved in the formation of the IR complex. The Hc-daf-2 gene was transcribed in all life stages of H. contortus, with a significant up-regulation in the iL3 compared with other stages. To compare patterns of expression between Hc-daf-2 and Ce-daf-2, reporter constructs fusing the Ce-daf-2 or Hc-daf-2 promoter to sequence encoding GFP were microinjected into the N2 strain of C. elegans, and transgenic lines were established and examined. Both genes showed similar patterns of expression in amphidial (head) neurons, which relate to sensation and signal transduction. Further study by heterologous genetic complementation in a daf-2-deficient strain of C. elegans (CB1370) showed partial rescue of function by Hc-daf-2. Taken together, these findings provide a first insight into the roles of Hc-daf-2/. Hc-DAF-2 in the biology and development of H. contortus, particularly in the transition to parasitism. © 2014 Australian Society for Parasitology Inc.
- Authors: Li, Facai , Lok, James , Gasser, Robin , Korhonen, Pasi , Sandeman, Mark , Shi, Deshi , Zhou, Rui , Li, Xiangrui , Zhou, Yanqin , Zhao, Junlong , Hu, Min
- Date: 2014
- Type: Text , Journal article
- Relation: International Journal for Parasitology Vol. 44, no. 7 (2014), p. 485-496
- Full Text:
- Reviewed:
- Description: Infective L3s (iL3s) of parasitic nematodes share common behavioural, morphological and developmental characteristics with the developmentally arrested (dauer) larvae of the free-living nematode Caenorhabditis elegans. It is proposed that similar molecular mechanisms regulate entry into or exit from the dauer stage in C. elegans, and the transition from free-living to parasitic forms of parasitic nematodes. In C. elegans, one of the key factors regulating the dauer transition is the insulin-like receptor (designated Ce-DAF-2) encoded by the gene Ce-daf-2. However, nothing is known about DAF-2 homologues in most parasitic nematodes. Here, using a PCR-based approach, we identified and characterised a gene (Hc-daf-2) and its inferred product (Hc-DAF-2) in Haemonchus contortus (a socioeconomically important parasitic nematode of ruminants). The sequence of Hc-DAF-2 displays significant sequence homology to insulin receptors (IR) in both vertebrates and invertebrates, and contains conserved structural domains. A sequence encoding an important proteolytic motif (RKRR) identified in the predicted peptide sequence of Hc-DAF-2 is consistent with that of the human IR, suggesting that it is involved in the formation of the IR complex. The Hc-daf-2 gene was transcribed in all life stages of H. contortus, with a significant up-regulation in the iL3 compared with other stages. To compare patterns of expression between Hc-daf-2 and Ce-daf-2, reporter constructs fusing the Ce-daf-2 or Hc-daf-2 promoter to sequence encoding GFP were microinjected into the N2 strain of C. elegans, and transgenic lines were established and examined. Both genes showed similar patterns of expression in amphidial (head) neurons, which relate to sensation and signal transduction. Further study by heterologous genetic complementation in a daf-2-deficient strain of C. elegans (CB1370) showed partial rescue of function by Hc-daf-2. Taken together, these findings provide a first insight into the roles of Hc-daf-2/. Hc-DAF-2 in the biology and development of H. contortus, particularly in the transition to parasitism. © 2014 Australian Society for Parasitology Inc.
First international external quality assessment scheme of nucleic acid amplification tests for the detection of schistosoma and soil-transmitted helminths, including strongyloides : A pilot study
- Cools, Piet, van Lieshout, Lisette, Koelewijn, Rob, Addiss, David, Ajjampur, Sitara, Ayana, Mio, Bradbury, Richard, Cantera, Jason, Dana, Daniel, Fischer, Kerstin, Imtiaz, Rubina, Kabagenyi, Joyce, Lok, James, McCarthy, James, Mejia, Rojelio, Mekonnen, Zeleke, Njenga, Sammy, Othman, Nurulhasanah, Shao, Hongguang, Traub, Rebecca, Van Esbroeck, Marjan, Vercruysse, Jozef, Vlaminck, Johnny, Williams, Steven, Verweij, Jaco, van Hellemond, Jaap, Levecke, Bruno
- Authors: Cools, Piet , van Lieshout, Lisette , Koelewijn, Rob , Addiss, David , Ajjampur, Sitara , Ayana, Mio , Bradbury, Richard , Cantera, Jason , Dana, Daniel , Fischer, Kerstin , Imtiaz, Rubina , Kabagenyi, Joyce , Lok, James , McCarthy, James , Mejia, Rojelio , Mekonnen, Zeleke , Njenga, Sammy , Othman, Nurulhasanah , Shao, Hongguang , Traub, Rebecca , Van Esbroeck, Marjan , Vercruysse, Jozef , Vlaminck, Johnny , Williams, Steven , Verweij, Jaco , van Hellemond, Jaap , Levecke, Bruno
- Date: 2020
- Type: Text , Journal article
- Relation: PLoS Neglected Tropical Diseases Vol. 14, no. 6 (2020), p. 1-19
- Full Text:
- Reviewed:
- Description: Background Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, Necator ameri-canus, Ancylostoma duodenale and A. ceylanicum), Strongyloides stercoralis and Schisto-soma in human stool. Currently, there is a large diversity of NAATs being applied, but an external quality assessment scheme (EQAS) for these diagnostics is lacking. An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. In the current study, we piloted an international EQAS for these helminths (i) to investigate the feasibility of designing and delivering an EQAS; (ii) to assess the diagnostic performance of laboratories; and (iii) to gain insights into the different NAAT protocols used. Methods and principal findings A panel of twelve stool samples and eight DNA samples was validated by six expert laboratories for the presence of six helminths (Ascaris, Trichuris, N. americanus, Ancylostoma, Strongyloides and Schistosoma). Subsequently this panel was sent to 15 globally dispersed laboratories. We found a high degree of diversity among the different DNA extraction and NAAT protocols. Although most laboratories performed well, we could clearly identify the laboratories that were poorly performing. Conclusions/Significance We showed the technical feasibility of an international EQAS for the NAAT of STHs, Stron-gyloides and Schistosoma. In addition, we documented that there are clear benefits for par-ticipating laboratories, as they can confirm and/or improve the diagnostic performance of their NAATs. Further research should aim to identify factors that explain poor performance of NAATs. © 2020 Cools et al.
- Authors: Cools, Piet , van Lieshout, Lisette , Koelewijn, Rob , Addiss, David , Ajjampur, Sitara , Ayana, Mio , Bradbury, Richard , Cantera, Jason , Dana, Daniel , Fischer, Kerstin , Imtiaz, Rubina , Kabagenyi, Joyce , Lok, James , McCarthy, James , Mejia, Rojelio , Mekonnen, Zeleke , Njenga, Sammy , Othman, Nurulhasanah , Shao, Hongguang , Traub, Rebecca , Van Esbroeck, Marjan , Vercruysse, Jozef , Vlaminck, Johnny , Williams, Steven , Verweij, Jaco , van Hellemond, Jaap , Levecke, Bruno
- Date: 2020
- Type: Text , Journal article
- Relation: PLoS Neglected Tropical Diseases Vol. 14, no. 6 (2020), p. 1-19
- Full Text:
- Reviewed:
- Description: Background Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, Necator ameri-canus, Ancylostoma duodenale and A. ceylanicum), Strongyloides stercoralis and Schisto-soma in human stool. Currently, there is a large diversity of NAATs being applied, but an external quality assessment scheme (EQAS) for these diagnostics is lacking. An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. In the current study, we piloted an international EQAS for these helminths (i) to investigate the feasibility of designing and delivering an EQAS; (ii) to assess the diagnostic performance of laboratories; and (iii) to gain insights into the different NAAT protocols used. Methods and principal findings A panel of twelve stool samples and eight DNA samples was validated by six expert laboratories for the presence of six helminths (Ascaris, Trichuris, N. americanus, Ancylostoma, Strongyloides and Schistosoma). Subsequently this panel was sent to 15 globally dispersed laboratories. We found a high degree of diversity among the different DNA extraction and NAAT protocols. Although most laboratories performed well, we could clearly identify the laboratories that were poorly performing. Conclusions/Significance We showed the technical feasibility of an international EQAS for the NAAT of STHs, Stron-gyloides and Schistosoma. In addition, we documented that there are clear benefits for par-ticipating laboratories, as they can confirm and/or improve the diagnostic performance of their NAATs. Further research should aim to identify factors that explain poor performance of NAATs. © 2020 Cools et al.
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