Researchers at McMaster have discovered that a sex-related gene in the African clawed frog\u00a0underwent strikingly different\u00a0functional\u00a0dynamics\u00a0in males\u00a0versus\u00a0females.\u00a0\u00a0<\/p>\n
This research helps scientists understand how the genetic underpinning of important traits like sex change over time, says Ben Evans, a professor in the Department of Biology and senior author of the study<\/a>.\u00a0<\/p>\n \u201cThis study shows us that small changes at a biological tipping point can snowball over development into massive differences, such as those between a female and a male body\u201d says Evans.\u00a0\u00a0<\/p>\n Researchers\u00a0examined the function of a gene called \u201cdoublesex\u00a0and mab-3 related transcription factor 1\u201d (dmrt1), which\u00a0influences sexual differentiation \u2013 the process by which an individual develops into a\u00a0male or\u00a0a\u00a0female.\u00a0<\/p>\n Ancestrally, the dmrt1 gene was essential for females to produce eggs, but when this gene was duplicated, that function was lost in one copy. In males, this gene was initially not essential for creating sperm, but after it was duplicated, one copy became essential for this crucial process. \u00a0<\/p>\n That means\u00a0that after this gene was duplicated, one copy became essential for fertility in\u00a0each\u00a0sex,\u00a0while the other became non-essential,\u00a0and\u00a0the evolutionary pathways\u00a0that led\u00a0to this changed function were different in each sex.\u00a0<\/p>\n Another gene in these frogs is found only in females and is the trigger for female development. Researchers were surprised to find this female-specific gene is derived from yet another duplication event \u2014 of the non-essential version of dmrt1.\u00a0<\/p>\n \u201cFrom an evolutionary standpoint, reproduction is one of the most important\u00a0things\u00a0an organism\u00a0needs to\u00a0do,\u201d says Evans. \u201cI find it surprising and interesting that this crucial process is now orchestrated by a copy of a gene that was non-essential.\u201d\u00a0<\/p>\n In this evolutionary process,\u00a0small differences\u00a0in the amount of\u00a0the gene end up having a large biological effect, he says: The duplicated non-essential copy of the dmrt1 gene leads to\u00a0a small change\u00a0that ends up taking over the entire system.\u00a0<\/p>\n \u201cOur findings help us understand how you can achieve large differences in adult male and female individuals that mostly share an identical genome. It\u2019s because the function of the same gene can be completely different, depending on whether that gene is in a male or a female individual.\u201d\u00a0<\/p>\n