Administration of cyclophosphamide to males targets the germ cells and causes DNA damage including single strand breaks and DNA-DNA cross links. When males are treated with a chronic low dose of cyclophosphamide and then mated to normal females, progeny loss is manifested at the pre- and post-implantation stages of development. The earliest events that lead to embryonic loss were traced to day 2 of gestation when embryos had a decreased DNA synthesis profile and lower cell numbers than control litters. I investigated the hypothesis that chronic exposure of male rats to cyclophosphamide alters zygotic gene expression thus leading to embryonic loss. To assess DNA damage in the embryo, the Comet Assay was performed on 1-cell stage embryos. A significant number of embryos sired by cyclophosphamide-treated males showed the appearance of the Comet indicative of the effect of damaged sperm on the embryos starting from the 1-cell stage. Using a candidate gene approach, the antisense RNA (aRNA), I described the presence of several DNA repair gene families in normal embryos. Progeny sired by cyclophosphamide-treated males manifested a differential expression profile for several of these genes when compared to controls, suggestive of the ability of the embryo to respond to damaged sperm through the major DNA repair systems. To study the functional capacity of progeny sired by cyclophosphamide-treated males, I assessed total RNA synthesis in both groups; while control litters showed a peak of RNA synthesis at the 4-cell stage, the treatment group showed constant low expression throughout the stages examined. I mapped the profile of a number of gene families whose roles are essential for early development in both control and cyclophosphamide-treated groups. While control embryos showed a peak of expression for the majority of genes at the 8-cell stage, that of the cyclophosphamide-group showed an early induction at the 2-cell stage, indicative of loss of the tightly regulated
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36604 |
| Date | January 2000 |
| Creators | Harrouk, Wafa. |
| Contributors | Hales, Barbara (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Pharmacology & Therapeutics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001754116, proquestno: NQ64572, Theses scanned by UMI/ProQuest. |
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