Marsupials and humans shared same genetic imprinting 150 million years ago

July 16th, 2008 - 3:45 pm ICT by ANI  

Melbourne, July 16 (ANI): A new research by a team of international scientists has determined that marsupials and humans shared the same genetic imprinting 150 million years ago.

The research team, which included the University of Melbourne, Department of Zoology, has established an identical mechanism of genetic imprinting, a process involved in marsupial and human fetal development, which evolved 150 million years ago.

According to Professor Geoffrey Shaw of the Department of Zoology at the University of Melbourne, a coauthor on the paper, This paper shows that we share a common genetic imprinting mechanism which has been active for about 150 million years despite the differences in reproductive strategies between marsupials and humans.

Professor Marilyn Renfree, who lead the University of Melbourne research team, said that marsupials give birth to very small young that develop mainly within the pouch while humans have more developed young at birth that undergo a large period of growth in the uterus.

Our team provided vital samples and genetic resources from marsupials to enable this study and contributed our world-leading expertise on marsupial biology and genomics to the interpretation of the results, said Professor Renfree.

Genomic imprinting is a mechanism that regulates gene expression in the developing fetus and plays a major role in regulating its growth.

We all carry two copies of every gene in our DNA, one inherited from our mother and one from our father. So for each gene we have a back-up. Normally, both copies of the gene are used for development, but in some special cases the gene from either our mother or father is switched off, so we only have one active copy. This phenomenon is known as genomic imprinting, explained Dr Andrew Pask also from the Department of Zoology.

Because there is no back up copy, when errors occur in this process, it results in many human genetic diseases mainly affecting growth and brain function, he added.

According to Pask, a key gene regulating fetal growth is the Insulin-like-growth-factor-2 or IGF2, which is an imprinted gene.

We inherit a single working copy of this gene from our fathers, while the copy we inherit from our mothers is switched off. The switch for this gene is controlled by another gene known as H19. The H19 gene is unusual gene that makes a microRNA and not a protein, he said.

MicroRNA genes have been sought in marsupials for years, and now for the first time one has been discovered, he added.

Understanding how genetic imprinting evolved is important, said Dr Shaw. It helps us to determine how the mechanism works and what we can do to avoid the development of a number of human diseases, he added. (ANI)

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