tag:blogger.com,1999:blog-3904639295706642486.post7693379977679231407..comments2023-10-21T08:48:37.363-07:00Comments on Zone-Reflex: Nature, nurture and natural selection. Epigenetic memory.Unknownnoreply@blogger.comBlogger3125tag:blogger.com,1999:blog-3904639295706642486.post-7478478198002685552013-02-08T12:23:39.842-08:002013-02-08T12:23:39.842-08:00http://www.biomedcentral.com/1741-7015/11/29/abstr...http://www.biomedcentral.com/1741-7015/11/29/abstract<br />the possible impact on the reprogramming of methylation profiles at imprinted genes at a much earlier time point, such as during spermatogenesis or oogenesis, has not previously been considered. In this study, our aim was to determine associations between preconceptional obesity and DNA methylation profiles in the offspring, particularly at the differentially methylated regions (DMRs) of the imprinted Insulin-like Growth Factor 2 (IGF2) gene. Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-37741716412400534752012-12-13T01:07:23.191-08:002012-12-13T01:07:23.191-08:00http://www.eurekalert.org/pub_releases/2012-12/nif...http://www.eurekalert.org/pub_releases/2012-12/nifm-sfe120612.php sex-specific epi-marks, which normally do not pass between generations and are thus "erased," can lead to homosexuality when they escape erasure and are transmitted from father to daughter or mother to son. Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-82860019338345949482012-11-24T00:16:10.692-08:002012-11-24T00:16:10.692-08:00http://www.mskcc.org/sites/www.mskcc.org/files/nod...http://www.mskcc.org/sites/www.mskcc.org/files/node/1522/documents/transcription.pdf<br /><br />Yeast growing for a considerable time in glucose ‘remember’ a previous exposure to galactose, the inducer of its galactose-utilization (GAL) genes. This memory is conveyed by a cytoplasmically transmitted<br />galactokinase working as a signal transducer.<br />The picture that emerges, then, is that growth in galactose causes expression to a high level of Gal1. Enough of this protein is then distributed to some six or seven generations’ worth of progeny cells produced in glucose so that, thanks to the Gal3-like activity of Gal1, those progeny cells induce quickly in response to galactose. Gal3 cannot confer memory simply because it is produced at a much lower level than Gal1, and so is quickly diluted out as the cells begin to divide.<br /><br />In the example of Zacharioudakis et al. [3], we see an example of a cytoplasmically transmitted protein that does not self-perpetuate itself, and so the life span of the memory, though considerable, is necessarily limited. The authors point out that the effect they analyze had previously been ascribed to ‘chromatin effects’. Perhaps this is not surprising: epigenetic changes are often defined as changes in chromatin modifications.<br /><br />‘‘The following could be a unifying definition of epigenetic events: the structural adaptation of chromosomal regions so as to register, signal or perpetuate altered activity states’’ [12]. Such definitions would exclude all cytoplasmically<br />transmitted epigenetic changes, including the lambda and prion cases, as well as the yeast example analyzed here. Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.com