Imprinting capacity of gamete lineages in Caenorhabditis
elegans
Ky Sha 1 and Andrew Fire 2*
1 Stanford University/Johns Hopkins
2 Stanford University
* To whom correspondence should be addressed. E-mail: afire{at}stanford.edu.
Submitted on December 27, 2004
Revised on February 10, 2005
Accepted on 11 April 2005
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Abstract |
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We have observed a gamete-of-origin imprinting effect in Caenorhabditis elegans using a set of GFP reporter transgenes. From a single progenitor line carrying an extra-chromosomal unc-54::gfp transgene array, we generated three independent autosomal integrations of the unc-54::gfp transgene. The progenitor line, two of its three integrated derivatives, and a non-related unc-119:gfp transgene exhibit an imprinting effect: single-generation transmission of these transgenes through the male germline results in approximately 1.5-2.0 fold greater expression than transmission through the female germline. There is a detectable resetting of the imprint after passage through the opposite germline for a single generation, indicating that the imprinted status of the transgenes is reversible. In cases where the transgene is maintained in either the oocyte lineage or sperm lineage for multiple, consecutive generations, a full reset requires passage through the opposite germline for several generations. Taken together, our results indicate that C. elegans has the ability to imprint chromosomes and that differences in the cell and/or molecular biology of oogenesis and spermatogenesis are manifest in an imprint that can persist in both somatic and germline gene expression for multiple generations.
Key Words:
C. elegans, Imprinting, Parent-of-origin effects, epigenetics, gene silencing
