On page 168, Dr. Shoalem Moalem discusses methylation and
the epigenome. Dr. Moalem specifically cites a 2004 study that showed
“interactions between mothers and their offspring after birth provoked the
placement of methyl markers caused significant epigenetic changes.”
The 2004 debate lends itself to the popular debate of nature
versus nurture. Dr. Moalem believes that the can be found between “nature and
nurture.” Interactions between mother rats with their offspring affected the
epigenome of the offspring, which changed the offspring’s ability to deal with
stress.
Define what the epigenome is. Explain how the epigenome is
modified (methylation, acetylation, etc.) Explain how these modifications in
the epigenome help regulate gene expression.
Define imprinting. How does the study Dr. Moalem cited
relate the epigenome and imprinting? Research and explain another example of
how care (nurture) can affect an offspring’s epigenome (nature).
(Dhruv Luthra, dluthra4@students.d125.org)
The epigenome can be defined as the chemical changes to an organisms DNA and histone proteins. Modifications to the epigenome alter the transcription of genes, and thus help regulate gene expression. Two of the main processes for modifying the epigenome are methylation and acetylation. In methylation, a methyl group is added to DNA, promoting the condensation of chromatin. This has the effect of reducing transcription of genes. On page 169, Dr. Moalem references a study that measured the methylation patterns in rat pups, noting that the "removal of methyl markers that would otherwise impeded the development...of their babies' brains". By the process of demethylation (the removal of methyl groups in DNA), transcription was promoted in the rat pups and their brains developed more than the rat pups with highly methylated DNA. Another epigenetic process is acetylation, in which acetyl groups are attached to the lysines in histone tails, making it easier for transcription proteins to access genes and begin transcription.
ReplyDeleteImprinting is the process by which an organism leans a behavior during a critical period, a time in which an organism has an increased sensitivity to external stimuli. The study cited by Dr. Moalem on page 169 suggests that the process of imprinting is related to epigenetic modifications. By grooming their rat pups, the mothers were able to demethylate the rat pups DNA and increase transcription. As Dr. Moalem says, "parental grooming was changing the expression of a living animal's genetic code" (169). Other studies have suggested that imprinting can modify the epigenome. In the study "Epigenetics in maternal nutrition: nature vs nurture" conducted by the University of Pennsylvania School of Medicine and the Department of Pediatrics at the Children's Hospital Philadelphia, it was discovered that maternal behaviors during pregnancy such as over- and under-eating altered the epigenome of their child, giving their child an increased risk of diseases such as diabetes and obesity.
This passage relates to the topics of epigenetics and gene expression, and imprinting and natural selection. All of these topics relate to Big Idea #1: The process of evolution drives the diversity and unity of life. Modifications to the epigenome alter the expression of genes in organisms, and imprinting has the ability to affect gene expression. The expression of different genes is the foundation of natural selection, as it produces variation within a population. Modifications to the epigenome can be a selective advantage or disadvantage to an organism, depending upon which genes are being turned on or shut off. In conclusion, epigenetic modification is a process that alters gene expression. This introduces variation into a population, which leads to natural selection.
REVISED RESPONSE:
ReplyDeleteThe epigenome can be defined as the chemical changes to an organisms DNA and histone proteins. Modifications to the epigenome alter the transcription of genes, and thus help regulate gene expression. Discover Magazine compares the epigenome to “a complex software code, capable of inducing the DNA hardware to manufacture an impressive variety of proteins, cell types, and individuals” (Watters 2006). Two of the main processes for modifying the epigenome are methylation and acetylation. In methylation, a methyl group is added to DNA, promoting the condensation of chromatin. This has the effect of reducing transcription of genes. On page 169, Dr. Moalem references a study that measured the methylation patterns in rat pups, noting that the "removal of methyl markers that would otherwise impeded the development...of their babies' brains". By the process of demethylation (the removal of methyl groups in DNA), transcription was promoted in the rat pups and their brains developed more than the rat pups with highly methylated DNA. Another epigenetic process is acetylation, in which acetyl groups attach to the lysines in histone tails. The positive charges on the lysines then neutralize and no longer bind to neighboring nucleosomes, loosening the chromatin structure and making it easier for transcription proteins to access genes and begin transcription (Campbell & Reece, 2008).
Imprinting is the process by which an organism learns a behavior during a critical period: a time in which an organism has an increased sensitivity to external stimuli. The study cited by Dr. Moalem on page 169 suggests that the process of imprinting is related to epigenetic modifications. By grooming their rat pups, the mothers were able to demethylate the rat pups DNA and increase transcription. As Dr. Moalem says, "parental grooming was changing the expression of a living animal's genetic code" (169). Other studies suggest that imprinting can modify the epigenome. In the study "Epigenetics in maternal nutrition: nature vs nurture" conducted by the University of Pennsylvania School of Medicine and the Department of Pediatrics at the Children's Hospital Philadelphia, scientists discovered that maternal behaviors during pregnancy such as over and under-eating altered the epigenome of their child, giving their child an increased risk of diseases such as diabetes and obesity.
This passage relates to the topics of epigenetics, gene expression, imprinting and natural selection. All of these topics relate to Big Idea #1: The process of evolution drives the diversity and unity of life. Modifications to the epigenome alter the expression of genes in organisms, and imprinting has the ability to affect gene expression. The expression of different genes is the foundation of natural selection, as it produces variation within a population. Modifications to the epigenome can be a selective advantage or disadvantage to an organism, depending upon which genes are being turned on or shut off. In conclusion, epigenetic modification is a process that alters gene expression. This introduces variation into a population, which leads to natural selection.