: Parasitic nematodes sicken or debilitate millions of persons worldwide. In the vast majority of these nematodes the third larval stage (L3) constitutes the infective stage for the vertebrate host. Regardless of how these L3 are acquired during the infection process, they may be viewed as transitional stages, in a state of developmental arrest, which are reactivated only when exposed to cues present in the definitive host. The mechanisms by which these parasites regulate development in the L3 remain unclear, studies in this area having been hampered by the lack of a molecular genetic system involving a parasitic nematode. By contrast, the developmental biology of L3, including the switch between continuous and arrested (dauer) development, has been under active investigation in the free-living nematode Caenorhabditis elegans, resulting in a wealth of relevant molecular genetic information on that organism. The overall goal of the proposed study is to ascertain whether mechanisms similar to those acting in C. elegans also regulate development in the parasite Strongyloides stercoralis. S. stercoralis was chosen as a model because, among numerous other functional and morphological similarities, this worm has an alternate free-living cycle reminiscent of the continuous developmental cycle of C. elegans.
The specific aims of this proposal are, first, to ascertain the existence in S. stercoralis of orthologs to four key genes on the insulin-like branch of the daf pathway, which controls development in C. elegans L3. Work toward this aim will stress a PCR approach involving primers based on published C. elegans gene sequences. Genes targeted for study are orthologs of C. elegans daf-2, age-1, daf-18 and daf-16. Second, we will investigate the function of the putative S. stercoralis daf orthologs. Functional homology of putative dauer inducing genes will be ascertained by methods such as inducing targeted mutations with chimeric RNA/DNA oligonucleotides and ablating specific transcripts with specific double stranded RNA. Homology of dauer inducers and putative dauer suppressing genes will be investigated by complementation and other transgenesis studies in appropriate C. elegans strains. Finally, we will endeavor to develop methods for germ line transformation of S. stercoralis in order to assess function of putative regulatory genes. Methods widely used for DNA transformation of C. elegans via microinjection into gonadal syncytia will be adapted.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI050668-02
Application #
6620421
Study Section
Tropical Medicine and Parasitology Study Section (TMP)
Program Officer
Rogers, Martin J
Project Start
2002-04-01
Project End
2005-03-31
Budget Start
2003-04-01
Budget End
2004-03-31
Support Year
2
Fiscal Year
2003
Total Cost
$390,985
Indirect Cost
Name
University of Pennsylvania
Department
Pathology
Type
Schools of Veterinary Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Arifin, Norsyahida; Yunus, Muhammad Hafiznur; Nolan, Thomas J et al. (2018) Identification and Preliminary Evaluation of a Novel Recombinant Protein for Serodiagnosis of Strongyloidiasis. Am J Trop Med Hyg 98:1165-1170
Lok, J B; Shao, H; Massey, H C et al. (2017) Transgenesis in Strongyloides and related parasitic nematodes: historical perspectives, current functional genomic applications and progress towards gene disruption and editing. Parasitology 144:327-342
Shao, Hongguang; Li, Xinshe; Lok, James B (2017) Heritable genetic transformation of Strongyloides stercoralis by microinjection of plasmid DNA constructs into the male germline. Int J Parasitol 47:511-515
Lok, James B (2016) Signaling in Parasitic Nematodes: Physicochemical Communication Between Host and Parasite and Endogenous Molecular Transduction Pathways Governing Worm Development and Survival. Curr Clin Microbiol Rep 3:186-197
Hunt, Vicky L; Tsai, Isheng J; Coghlan, Avril et al. (2016) The genomic basis of parasitism in the Strongyloides clade of nematodes. Nat Genet 48:299-307
Mohandas, Namitha; Hu, Min; Stroehlein, Andreas J et al. (2016) Reconstruction of the insulin-like signalling pathway of Haemonchus contortus. Parasit Vectors 9:64
Albarqi, Mennatallah M Y; Stoltzfus, Jonathan D; Pilgrim, Adeiye A et al. (2016) Regulation of Life Cycle Checkpoints and Developmental Activation of Infective Larvae in Strongyloides stercoralis by Dafachronic Acid. PLoS Pathog 12:e1005358
Wang, Zhu; Stoltzfus, Jonathan; You, Young-Jai et al. (2015) The nuclear receptor DAF-12 regulates nutrient metabolism and reproductive growth in nematodes. PLoS Genet 11:e1005027
Yuan, Wang; Liu, Yingying; Lok, James B et al. (2014) Exploring features and function of Ss-riok-3, an enigmatic kinase gene from Strongyloides stercoralis. Parasit Vectors 7:561
Li, Fa-Cai; Gasser, Robin B; Lok, James B et al. (2014) Exploring the role of two interacting phosphoinositide 3-kinases of Haemonchus contortus. Parasit Vectors 7:498

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