Why are genetically identical individuals different? Ask your mum!

Why are genetically identical individuals different? Ask your mum!

Does the age of a mother influence the traits and characteristics of her progeny, and how? A team of scientists addressed these questions by studying tiny, genetically identical C. elegans worms. Their results have been published in Nature.

"Our lab has long been interested in understanding why genetically identical individuals sharing the same environment still often differ substantially in their characteristics," explains the senior author. "Through a rather circuitous route, we have now identified a major cause of these differences in one of the main model organisms that we study."

"We observed that the age of a mother has a major impact on the physiology of her offspring" states co-first author of this work. "Surprisingly we found that it is the youngest mothers that produce offspring that are impaired for many characteristics such as their size, growth rate, and starvation resistance" explains the other co-first author of the study. "The offspring of young mothers also have fewer offspring themselves when they become adults," the co-author adds.

"These differences are caused in part because young mothers provide less of a specific protein complex to their embryos," adds the senior author. Why would a worm produce low quality progeny early in life? "Producing progeny early in life, even if they are lower quality, has a major benefit because it dramatically shortens the generation time of the species," explains the senior author.

"What's particularly interesting is that the age of an individual's mother determines their characteristics throughout their lives," adds another author. "This is a really interesting example of how the physiology of a previous generation can alter not only the development of an animal but also its characteristics as a mature adult."

Authors identify age-dependent changes in the maternal provisioning of the lipoprotein complex vitellogenin to embryos as the molecular mechanism that underlies the variation in multiple traits throughout the life of an animal. 

"Our results are also important for the thousands of people doing research in this species. People don't consider maternal age when designing experiments but now we have shown that it is an important factor," conclude the scientists.