Helen's review of the last paper
Mechanisms for the environmental regulation of gene expression: Ecological aspects of animal development (Gilbert, 2005)
This is the most recent in a series of papers published by Gilbert in which he introduces the concept of ecological developmental biology. Gilbert commences with a historical account of the degree of focus (or neglect) that environmental factors have received in the study of normal development. Throughout much of the 20th century, researchers have focussed on minimising environmental variation to maintain repeatability in the laboratory environment. However, it is becoming clear that the majority of organisms interact directly with the environment during development, and that the correct environmental conditions can have an instructive role in normal development. This paper links environmentally sensitive processes to specific regulatory networks. Gilbert explores three different mechanisms. 1. The neuroendocrine system can monitor the environment and transfer signals to the endocrine system, which can alter gene expression. For example, the butterfly Araschina levana has vastly different wingspot patterns due to seasonal temperatures, which can be reproduced in the laboratory. The titre of the hormone ecdysone is environmentally sensitive, and ecdysone expression directly impacts the expression of patterning genes. This presents a likely explanation for the seasonality of wingspot patterns. Other examples include temperature-driven sex determination in reptiles, and the interaction between the mammalian foetus and mother. 2. Environmental factors can change the methylation pattern of genes, thereby altering their transcriptional capabilities. It has been established in mice that dietary intake of methyl donors (eg. Folate) can influence the methylation state of genes, which can have a subsequent influence on phenotype. 3. Microbial symbionts can directly impact gene expression. The impact of mammalian gut flora on gene expression and gut differentiation was discussed.
This is the most mechanistic paper to date, but some of the earlier ones present a better historical account. Email me if you are interested.
posted by John S. Wilkins @ 6:14 PM
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