Discoveries and advances in the field of epigenetics
David Haig, associate professor of organismic and evolutionary biology at Harvard University, is interviewed in ten questions with Razib at Gene Expression. The interview covers a number of topics on genomic imprinting, as well as the role of epistasis in evolutionary processes, maternally- and paternally-expressed genes, and the potential effects of deleterious mutations on the human population. Link
Permalink Comments off
Evolutionary biologist David Crews and colleague John McLachlan have published an interesting paper in the endocrine disruptor supplement in the June edition of the journal Endocrinology entitled “Epigenetics, Evolution, Endocrine Disruption, Health, and Disease.” The paper takes a closer look at some of the key research findings made in the last year in the area of epigenetics and how epigenetic modifications passed on to multiple generations may “become incorporated into the genome and subject to selection.”
The second issue of the Journal of Epigenetics is now (partially) available online, with free online access to this new journal through the end of 2006. The issue contains an informative historical overview of the field of epigenetics, beginning with the coinage of the term “epigenetics” by Conrad Waddington to help merge the fields of developmental biology and genetics.
Building on the work of Waddington and others, the article delves further into the efforts made by scientists over the last thirty years to explain how some differentiated cell types, such as fibroblasts and lymphocytes, “stably maintain their phenotype through cell division.” The notion that the methylation of DNA could affect gene expression, and that these methylation patterns could be heritable, was proposed independently by two groups in 1975. That same year, other papers were published exploring the possibilities that eukaryotic organisms contained enzymes that restrict unmodified DNA, and that methylation patterns in cancer cells could affect gene expression. Interestingly, none of the papers used the word “epigenetics.”
Author Robin Holliday also uses this publication to review the two definitions for epigenetics that were proposed in 1994, along with the role that his own 1987 paper, “The inheritance of epigenetic defects,” played in increasing the use of the word “epigenetics” throughout the 1990’s.
Other important topics discussed in this paper are the key differences between genetic and epigenetic mechanisms, the potential role and evidence for chromatin configuration affecting epigenetic inheritance, and the importance of clearly defined terminology, such as “epigenotypes,” as The Human Epigenome Project attempts to get underway. Link
Permalink Comments off
The Journal of Evolutionary Biology has published a mini-review ahead of print that proposes a new evolutinary theory for the aetiology of autism. Dr. Christopher Badcock and Professor Bernard Crespi propose that autism has been developed through “imbalances in brain development involving enhanced effects of paternally expressed imprinted genes, deficits of effects from maternally expressed genes, or both.”
The proposed theory builds on Baron-Cohen’s “extreme male brain theory” of autism, which the authors claim fails to account for the high incidence of autistic males that are more towards the “normal” end of the spectrum. Additionally, Badcock and Crespi have trouble reconciling the extreme male brain theory of autism with the incidence of any female cases of the disorder.
Rather, the authors suggest a new “extreme imprinted brain theory” that accounts for the sex ratio biases of autism (approximately 4:1 ratio of males to females) and “other observations that are otherwise inexplicable.”
Imbalanced genomic imprinting in brain development: an evolutionary basis for aetiology of autism
Trevor R. Covert is a graduate of Washington State University (Genetics and Cell Biology, Molecular Biology) in Pullman, Wa. His current research in the lab of Dr. Michael Skinner is investigating the transgenerational effects of endocrine disruptors. Read more about Epigenetics News.
Recent Epigenetics Research