Genomic imprinting--defusing the ovarian time bomb.
Why do mammals imprint their parental genomes? Imprinting is seen in many phyla, but that in mammals is by far the most dramatic. Is there something peculiar to mammals that calls for such a striking phenomenon? We propose that imprinting is a device that protects female mammals from the potential ravages of ovarian trophoblast disease. Without imprinting, the ovarian teratomas that frequently arise from parthenogenetically activated oocytes in situ might be capable of forming malignant trophoblast. An allele that favored imprinting would spread rapidly because of the great increase in fitness associated with suppressing a lethal cancer of females.
Department of Zoology, University of Toronto, Ontario, Canada.
S
S
Varmuza
M
M
Mann
D000483:Alleles; D000818:Animals; D002822:Choriocarcinoma / Q000235:genetics*; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D008297:Male; D008322:Mammals / Q000235:genetics; D008745:Methylation; D051379:Mice; D008954:Models, Biological; D009865:Oocytes / Q000473:pathology; D010051:Ovarian Neoplasms / Q000235:genetics*; D010290:Parents; D010312:Parthenogenesis; D010641:Phenotype; D011247:Pregnancy; D012641:Selection, Genetic; D013724:Teratoma / Q000235:genetics*; D013736:Testicular Neoplasms / Q000235:genetics; D014328:Trophoblastic Neoplasms / Q000235:genetics*; D014594:Uterine Neoplasms / Q000235:genetics*