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Reproductive biology and cell-cell interactions in C. elegans Fertilization is a biological process that has important social, economic and medical implications. Our primary research interest is the mechanisms of sperm-egg interactions. The long-term goal of research in the lab is to understand the molecular events that mediate gamete recognition, adhesion, signaling and fusion. The genetic and molecular dissection of these events will also provide insights relevant to other important cell-cell interactions during the development of multicellular organisms. We are helping to pioneer the use of the nematode worm Caenorhabditis elegans for addressing the mechanisms of sperm-egg interactions. The powerful tools of classical and molecular genetics developed for the worm are not available or are very difficult to utilize in the other organisms traditionally used for studying fertilization. The ameboid sperm of C. elegans, despite lacking an acrosome and flagellum, carry out the same basic functions common to all spermatozoa. The reproductive biology of C. elegans facilitates the identification of mutations that affect sperm and no other cells. The worm exists as a hermaphrodite that makes both sperm and oocytes or as a male that makes only sperm. Mutant hermaphrodites that are spermatogenesis-defective (spe) are self-sterile and lay unfertilized oocytes. However, when these otherwise healthy worms are crossed to wild type males (a source of sperm) they can produce outcrossed progeny. We have focused on a set of spe genes that produce sperm with normal morphology and motility that cannot fertilize eggs even after contact. From this phenotype we infer that these mutants disrupt either sperm-egg recognition, adhesion, signaling or fusion. The characterization of these genes is a critical step in formulating a model concerning their role in wild-type fertilization. Since we expect that not every gene required for fertilization will be sperm specific, we are employing both forward and reverse genetic approaches to identify additional genes required for fertility in C. elegans. Our work on C. elegans reproductive biology complements studies of fertilization in other organisms and provides insights relevant to the understanding of cell-cell interactions. Publications I. Chatterjee, P. Kadandale and A. Singson. (2006) Meiotic diapause: how a sperm signal sets you free. Current Biology 16: R496-R499. Pubmed abstract A. Singson. (2006) Sperm activation: time and tide wait for no sperm. Current Biology 16: R160-R162. Pubmed abstract B. Geldziler, I. Chatterjee, P. Kadandale, E. Putiri, R. Patel and A. Singson. (2006) A comparative study of sperm morphology, cytology and activation in Caenorhabditis elegans, Caenrohabditis remanei and Caenorhabditis briggsae. Development, Genes and Evolution 216: 198-208. Pubmed abstract E. J. Gleason, W. C. Lindsey, T. L. Kroft, A. W. Singson and S. W. L’Hernault. (2006) spe-10 Encodes a DHHC-CRD zinc finger membrane protein required for ER/golgi membrane morphogenesis during Caenorhabditis elegans spermatogenesis. Genetics 172: 145-158. Pubmed abstract P. Kadandale, A. Stewart-Michaelis, S. Gordon, J. Rubin, R. Klancer, P. Schweinsberg, B. D. Grant and A. Singson. (2005) The egg surface LDL-receptor-repeat containing proteins EGG-1 and EGG-2 are required for fertilization in Caenorhabditis elegans. Current Biology 15: 2222-2229.
P. Kadandale, B. Geldziler, M. Hoffman, and A. Singson. (2005) Use of SNPs to determine the breakpoints
of complex deficiencies, facilitating gene mapping in Caenorhabditis elegans. BMC Genetics 2005,
6:28. B. Geldziler, I. Chatterjee, and A. Singson. (2005) The genetic and molecular analysis of spe-19, a gene required for sperm activation in Caenorhabditis elegans. Developmental Biology 283: 424-436 . Pubmed abstract I. Chatterjee, A. Richmond, E. Putiri, D. C. Shakes, and A. Singson. (2005) The Caenorhabditis elegans spe-38 gene encodes a novel four pass integral membrane protein required for sperm function at fertilization. Development, 132: 2795-2808. Pubmed abstract | Publisher abstract E. Putiri, S. Zannoni, P. Kadandale, and A. Singson. (2004) Functional domains and temperature sensitive mutations in SPE-9, an EGF repeat containing protein required for fertility in Caenorhabditis elegans. Developmental Biology. 272: 448-459. Pubmed abstract | Publisher fulltext P. Kadandale and A. Singson. (2004) Oocyte production and sperm utilization patterns in semi-fertile strains of Caenorhabditis elegans. BMC Developmental Biology. 2004 Apr 15; 4(1):3. Pubmed abstract | Publisher abstract | Article PDF
B. Geldziler, P. Kadandale and A. Singson. (2004)
Molecular genetic approaches to studying fertilization in model systems.
Reproduction. 127: 409-416.
S. Zannoni, S. W. L'Hernault and A. W. Singson (2003)
Dynamic localization of SPE-9 in sperm: a protein required for sperm-oocyte interactions in
Caenorhabditis elegans.
BMC Developmental Biology. 2003 Dec 3; 3(1):10. J. Bandyopadhyay, J. Lee, J. Lee, J. I. Lee, J. R. Yu, C. Jee, J. H. Cho, S. Jung, M. H. Lee, S. Zannoni, A. Singson, H. S. Koo and J. Ahnn. (2002) Calcineurin, a component of G-protein coupled phosphorylation pathways, is involved in movement, fertility, egg laying and growth in C. elegans. Molecular Biology of the Cell. 13: 3281-3293. Pubmed abstract | Publisher abstract
B. Park, D. Lee, S. Jung, J. Yu, K. Choi, J. Y. Kwon, J. Lee, J. Lee, A. Singson, W. K. Song, C. S. Park,
D. H. Kim, J. Bandyopadhyay and J. Ahnn. (2001)
Calreticulin, a calcium-binding molecular chaperone is required for stress response and sperm fertility in
C. elegans.
Molecular Biology of the Cell. 12: 2835-2845.
A. Singson, P. Kadandale and S. Zannoni. (2001)
Molecules that Function in the Steps of Fertilization.
Cytokine & Growth Factor Reviews. 12: 299-304. R. E. Navarro, E. Y. Shim, Y. Kohara, A. Singson and T.K. Blackwell. (2001) cgh-1, a Conserved Predicted RNA Helicase Required for Gametogenesis and Inhibition of Germline Apoptosis in' C. elegans. Development. 128: 3221-3232. Pubmed abstract | Publisher abstract A. Singson. (2001) Every Sperm is Sacred: Fertilization in C. elegans. Developmental Biology. 230: 101-109. Pubmed abstract | Article PDF S. W. L'Hernault and A. Singson. (2000) Developmental Genetics of Spermatogenesis in the Nematode Caenorhabditis elegans. In: The Testes: From Stem Cell to Sperm Function, Serono Symposium USA, 109-119.
A. Singson, K. L. Hill and S. W. L'Hernault. (1999)
Sperm Competition in the Absence of Fertilization in Caenorhabditis elegans.
Genetics. 152: 201-208.
A. Singson, K. B. Mercer and S. W. L'Hernault. (1998)
The C. elegans spe-9 Gene Encodes a Sperm Transmembrane Protein that Contains EGF-Like Repeats
and is Required for Fertilization.
Cell. 93: 71-79. Lab
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