Epigenetics (abstracts)
From ResearchID.org
Epigenetics is emerging as one of the most important topics impinging upon the intelligent design and evolution. The following is a page of abstracts from papers that deal with issues that may have a direct impact on future ID research.
- Galagan JE, Selker EU. (2004) RIP: the evolutionary cost of genome defense. Trends Genet. 2004 Sep;20(9):417-23.
Abstract
Repeat-induced point mutation (RIP) is a homology-based process that mutates repetitive DNA and frequently leads to epigenetic silencing of the mutated sequences through DNA methylation. Consistent with the hypothesis that RIP serves to control selfish DNA, an analysis of the Neurospora crassa genome sequence reveals a complete absence of intact mobile elements. As in most eukaryotes, the centromeric regions of N. crassa are rich in sequences that are related to transposable elements; however, in N crassa these sequences have been heavily mutated. The analysis of the N. crassa genome sequence also reveals that RIP has impacted genome evolution significantly through gene duplication, which is considered to be crucial for the evolution of new functions. Most if not all paralogs in N. crassa duplicated and diverged before the emergence of RIP. Thus, RIP illustrates the extraordinary extent to which genomes will go to defend themselves against mobile genetic elements.
- Sara M. (2001) Biological evolution as an expression of body-plan potentialities. Riv Biol. 2001 Sep-Dec;94(3):469-85.
Abstract
A growing bulk of recent data from different fields as molecular biology, developmental biology, genetics, paleontology and phylogenetics shows that organisms play a more active role in their evolution than what postulated by the random variation-natural selection paradigm of the neo-Darwinian synthesis. Organisms show during development and morphogenesis autopoietic processes which are related to their body-plan potentialities. These potentialities are expressed through regulatory networks in which a plastic genome participates together with proteins and other substances in an epigenetic space. The epigenetic systems which arise from this interaction may be inherited and then assume a significant role in evolution becoming the source of new acquired characters. The acquisition of new traits through the epigenetic systems is influenced directly by environmental cues. If this process is coherent with the environmental demands it co-operates with natural selection in organism adaptation. An outstanding role in this context may be played by phenotypic plasticity if, as emerges in recent views, it may constitute a general basis for genetic assimilation processes.
- Sara M. (1996) A "sensitive" cell system. Its role in a new evolutionary paradigm. Riv Biol. 1996;89(1):139-56. [Article in English, Italian]
Abstract
The cell property of processing the environmental information is called sensitivity and referred to a "sensitive" cell system in which physical signals and specialized molecules work in relation to peculiar cell structures. It is suggested that, in addition to its role in cell behaviour, the sensitive system performs a basic role in morphogenesis in all cells. It interacts with the genetic system in gene expression and regulation directly or indirectly through epigenetic processes. Epigenetic inheritance, adaptive mutations and genetic assimilation allow environmental information to be embodied in new traits, thereby becoming relevant in evolution. This is consistent with an evolutionary mechanism with two alternate and recurrent phases: the first, epigenetic and Lamarckian at cell and organism levels and the second, selective and Darwinian, at population level.
- Ho MW, Saunders PT (1979) Beyond neo-Darwinism--an epigenetic approach to evolution. J Theor Biol. 1979 Jun 21;78(4):573-91.
Abstract
We argue that the basic neo-Darwinian framework—the natural selection of random mutations—is insufficient to account for evolution. The role of natural selection is itself limited: it cannot adequately explain the diversity of populations or of species; nor can it account for the origin of new species or for major evolutionary change. The evidence suggests on the one hand that most genetic changes are irrelevant to evolution; and on the other, that a relative lack of natural selection may be the prerequisite for major evolutionary advance.
Contrary to the neo-Darwinian view, we point out that the variations of the phenotype, on which natural selection could act, do not arise at random; they are produced by interactions between the organism and the environment during development. We propose, therefore, that the intrinsic dynamical structure of the epigenetic system itself, in its interaction with the environment, is the source of non-random variations which direct evolutionary change, and that a proper study of evolution consists in the working out of the dynamics of the epigenetic system and its response to environmental stimuli as well as the mechanisms whereby novel developmental responses are canalized.
We postulate that “large” evolutionary changes could be the result of the canalization of novel developmental responses which arose from environmental challenges under conditions of relaxed natural selection, and moreover, that the canalization of novel developmental responses might involve cytoplasmic inheritance or maternal effects at least in the initial stages.
- Elena SF, Sanjuan R. (2003) Evolution. Climb every mountain? Science. 2003 Dec 19;302(5653):2074-5.
Comment on: Science. 2003 Dec 19;302(5653):2107-9.
Abstract
Evolutionary biologists have long argued that adaptation to a particular environmental niche should constrain a population's ability to survive in other niches. In their Perspective, Elena and Sanjuán discuss new evolution experiments with populations of the bacterium Pseudomonas fluorescens (Buckling et al.). These experiments provide evidence that as a bacterial population becomes a niche specialist, it is less able to adapt to other niches.
