Epigenetics and the renaissance of heresy

Genome ◽  
2003 ◽  
Vol 46 (6) ◽  
pp. 963-967 ◽  
Author(s):  
Susannah Varmuza
Keyword(s):  
Dna Sequence ◽  
Driving Forces ◽  
Position Effect ◽  
Epigenetic Inheritance ◽  
Evolutionary Change ◽  
Chromosome Rearrangements ◽  
Phenotypic Change ◽  
Position Effects ◽  
Darwinian Theory ◽  
Richard Goldschmidt

Classic neo-Darwinian theory is predicated on the notion that all heritable phenotypic change is mediated by alterations of the DNA sequence in genomes. However, evidence is accumulating that stably heritable phenotypes can also have an epigenetic basis, lending support to the long-discarded notion of inheritance of acquired traits. As many of the examples of epigenetic inheritance are mediated by position effects, the possibility exists that chromosome rearrangements may be one of the driving forces behind evolutionary change by exerting position effect alterations in gene activity, an idea articulated by Richard Goldschmidt. The emerging evidence suggests that Goldschmidt's controversial hypothesis deserves a serious reevaluation.Key words: epigenetics, position effects, inheritance of acquired traits.

scholarly journals Position effect variegation in Drosophila melanogaster: relationship between suppression effect and the amount of Y chromosome.

Genetics ◽  
1989 ◽  
Vol 122 (4) ◽  
pp. 793-800 ◽  
Author(s):  
P Dimitri ◽  
C Pisano
Keyword(s):  
Drosophila Melanogaster ◽  
Y Chromosome ◽  
Position Effect ◽  
Chromosome Rearrangements ◽  
Position Effect Variegation ◽  
Position Effects ◽  
Suppression Effect ◽  
Genetic Nature ◽  
Cell Clones ◽  
Effect Variegation

Abstract Position effect variegation results from chromosome rearrangements which translocate euchromatic genes close to the heterochromatin. The euchromatin-heterochromatin association is responsible for the inactivation of these genes in some cell clones. In Drosophila melanogaster the Y chromosome, which is entirely heterochromatic, is known to suppress variegation of euchromatic genes. In the present work we have investigated the genetic nature of the variegation suppressing property of the D. melanogaster Y chromosome. We have determined the extent to which different cytologically characterized Y chromosome deficiencies and Y fragments suppress three V-type position effects: the Y-suppressed lethality, the white mottled and the brown dominant variegated phenotypes. We find that: (1) chromosomes which are cytologically different and yet retain similar amounts of heterochromatin are equally effective suppressors, and (2) suppression effect is positively related to the size of the Y chromosome deficiencies and fragments that we tested. It increases with increasing amounts of Y heterochromatin up to 60-80% of the entire Y, after which the effect reaches a plateau. These findings suggest suppression is a function of the amount of Y heterochromatin present in the genome and is not attributable to any discrete Y region.

scholarly journals Activator-independent gene expression in Neurospora crassa

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 417-423
Author(s):  
Wayne K Versaw ◽  
Robert L Metzenberg
Keyword(s):  
Gene Expression ◽  
Neurospora Crassa ◽  
Chromosomal Rearrangement ◽  
Position Effect ◽  
Upstream Region ◽  
Phosphorus Metabolism ◽  
Position Effects ◽  
Cis Acting ◽  
Independent Gene ◽  
Acting Mechanism

Abstract A transgenic position effect that causes activator-independent gene expression has been described previously for three Neurospora crassa phosphate-repressible genes. We report analogous findings for two additional positively regulated genes, qa-2  + and ars-1  +, indicating that such position effects are not limited to genes involved in phosphorus metabolism. In addition, we have characterized a number of mutants that display activator-independent gene expression. Each of these mutants contains a chromosomal rearrangement with one breakpoint located in the 5’-upstream region of the affected gene. This suggests that the rearrangements are associated with activator-independent gene expression and that these cis-acting mutations may represent a position effect similar to that responsible for rendering some transgenes independent of their transcriptional activators. We suggest that positively regulated genes in N.  crassa are normally held in a transcriptionally repressed state by a cis-acting mechanism until specifically activated. Disruption of this cis-acting mechanism, either by random integration of a gene by transformation or by chromosomal rearrangement, renders these genes independent or partly independent of the transcriptional activator on which they normally depend.

pitkinD, a Novel Gain-of-Function Enhancer of Position-Effect Variegation, Affects Chromatin Regulation During Oogenesis and Early Embryogenesis in Drosophila

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1227-1244 ◽  
Author(s):  
Steffi Kuhfittig ◽  
János Szabad ◽  
Gunnar Schotta ◽  
Jan Hoffmann ◽  
Endre Máthé ◽  
...  
Keyword(s):  
Germ Line ◽  
Position Effect ◽  
Early Embryogenesis ◽  
Position Effect Variegation ◽  
Chromatin Regulation ◽  
Gain Of Function ◽  
Position Effects ◽  
Dominant Female ◽  
Effect Variegation ◽  
Female Germ Line

Abstract The vast majority of the >100 modifier genes of position-effect variegation (PEV) in Drosophila have been identified genetically as haplo-insufficient loci. Here, we describe pitkinDominant (ptnD), a gain-of-function enhancer mutation of PEV. Its exceptionally strong enhancer effect is evident as elevated spreading of heterochromatin-induced gene silencing along euchromatic regions in variegating rearrangements. The ptnD mutation causes ectopic binding of the SU(VAR)3-9 heterochromatin protein at many euchromatic sites and, unlike other modifiers of PEV, it also affects stable position effects. Specifically, it induces silencing of white+ transgenes inserted at a wide variety of euchromatic sites. ptnD is associated with dominant female sterility. +/+ embryos produced by ptnD/+ females mated with wild-type males die at the end of embryogenesis, whereas the ptnD/+ sibling embryos arrest development at cleavage cycle 1-3, due to a combined effect of maternally provided mutant product and an early zygotic lethal effect of ptnD. This is the earliest zygotic effect of a mutation so far reported in Drosophila. Germ-line mosaics show that ptn+ function is required for normal development in the female germ line. These results, together with effects on PEV and white+ transgenes, are consistent with the hypothesis that the ptn gene plays an important role in chromatin regulation during development of the female germ line and in early embryogenesis.

scholarly journals Computational Prediction of Position Effects of Human Chromosome Rearrangements

2018 ◽  
Vol 97 (1) ◽  
pp. e57
Author(s):  
Cinthya J. Zepeda-Mendoza ◽  
Shreya Menon ◽  
Cynthia C. Morton
Keyword(s):  
Human Chromosome ◽  
Computational Prediction ◽  
Chromosome Rearrangements ◽  
Position Effects

The effects of chromosome rearrangements on the expression of heterochromatic genes in chromosome 2L of Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 125 (1) ◽  
pp. 141-154 ◽  
Author(s):  
B T Wakimoto ◽  
M G Hearn
Keyword(s):  
Drosophila Melanogaster ◽  
Chromosome Rearrangements ◽  
Centromeric Heterochromatin ◽  
Chromosome 2 ◽  
Regulatory Requirement ◽  
Position Effects ◽  
Heterochromatic Genes

Abstract The light (lt) gene of Drosophila melanogaster is located at the base of the left arm of chromosome 2, within or very near centromeric heterochromatin (2Lh). Chromosome rearrangements that move the lt+ gene from its normal proximal position and place the gene in distal euchromatin result in mosaic or variegated expression of the gene. The cytogenetic and genetic properties of 17 lt-variegated rearrangements are described in this report. We show that five of the heterochromatic genes adjacent to lt are subject to inactivation by these rearrangements and that the euchromatic loci in proximal 2L are not detectably affected. The properties of the rearrangements suggest that proximity to heterochromatin is an important regulatory requirement for at least six 2Lh genes. We discuss how the properties of the position effects on heterochromatic genes relate to other proximity-dependent phenomena such as transvection.

The heterochromatin-associated protein HP-1 is an essential protein in Drosophila with dosage-dependent effects on position-effect variegation.

Genetics ◽  
1992 ◽  
Vol 131 (2) ◽  
pp. 345-352 ◽  
Author(s):  
J C Eissenberg ◽  
G D Morris ◽  
G Reuter ◽  
T Hartnett
Keyword(s):  
Germ Line ◽  
Position Effect ◽  
Inducible Promoter ◽  
Specific Protein ◽  
P Element ◽  
Position Effect Variegation ◽  
Chromosomal Protein ◽  
Gene Encoding ◽  
Position Effects ◽  
Effect Variegation

Abstract Chromosome rearrangements which place euchromatic genes adjacent to a heterochromatic breakpoint frequently result in gene repression (position-effect variegation). This repression is thought to reflect the spreading of a heterochromatic structure into neighboring euchromatin. Two allelic dominant suppressors of position-effect variegation were found to contain mutations within the gene encoding the heterochromatin-specific chromosomal protein HP-1. The site of mutation for each allele is given: one converts Lys169 into a nonsense (ochre) codon, while the other is a frameshift after Ser10. In flies heterozygous for one of the mutant alleles (Su(var)2-504), a truncated HP-1 protein was detectable by Western blot analysis. An HP-1 minigene, consisting of HP-1 cDNA under the control of an Hsp70 heat-inducible promoter, was transduced into flies by P element-mediated germ line transformation. Heat-shock driven expression of this minigene results in elevated HP-1 protein level and enhancement of position-effect variegation. Levels of variegating gene expression thus appear to depend upon the level of expression of a heterochromatin-specific protein. The implications of these observations for mechanism of heterochromatic position effects and heterochromatin function are discussed.

Order effects and multi-city visits: tour guides’ perspectives

2018 ◽  
Vol 4 (2) ◽  
pp. 194-206 ◽  
Author(s):  
Samira Zare ◽  
Philip Pearce
Keyword(s):  
Position Effect ◽  
Order Effects ◽  
Position Effects ◽  
Content Type ◽  
Tour Guides ◽  
High Profile ◽  
Large Numbers ◽  
Perceived Effects ◽  
Guided Tours ◽  
Practical Implications

Purpose The purpose of this paper is to examine the influence of the order in which a set of cities are visited to ascertain the effects of position on group tourists’ recall and evaluations. Design/methodology/approach Using a questionnaire, the views of highly experienced tour guides were analysed to provide preliminary insights about the likely occurrence of position effects. The topic was studied in Iran where a natural variation in the order of visiting cities on guided tours exists. Findings Credible and consistent evidence was found for the perceived effects of recency when considering tourists’ recall and evaluations. In particular, the influence was seen as clearly enhancing the recall and positive evaluation for the most high profile cities in the set of visited locations. Research limitations/implications Replications of the position effect in other countries and for other kinds of tourism cities needs to be pursued, desirably by direct assessments of tourist’ views to buttress the present views held by guides. Practical implications Designing itineraries by making imaginative use of the effects of order on the tourists’ sequence of city visits should facilitate the memorability of destinations for tourists and benefit businesses. Originality/value Empirical evidence about order effects in multi-city tour itineraries has never been established. The study provides foundation evidence for such influences through a non-reactive and naturalistic assessment by tour guides who are in contact with varied itineraries and who regularly consider the experiences of diverse and large numbers of tourists.

Environmental impacts on sperm and oocyte epigenetics affect embryo cell epigenetics and transcription to promote the epigenetic inheritance of pathology and phenotypic variation

2021 ◽  
Vol 33 (2) ◽  
pp. 102
Author(s):  
Eric Nilsson ◽  
Millissia Ben Maamar ◽  
Michael K. Skinner
Keyword(s):  
Gene Expression ◽  
Germ Cell ◽  
Germ Cells ◽  
Subsequent Development ◽  
Epigenetic Inheritance ◽  
Embryo Cell ◽  
Phenotypic Change ◽  
Epigenetic Changes ◽  
Epigenetic Alterations ◽  
Non Coding Rna

Previous studies have demonstrated that exposure to environmental factors can cause epigenetic modifications to germ cells, particularly sperm, to promote epigenetic and transcriptome changes in the embryo. These germ cell and embryo cell epigenetic alterations are associated with phenotypic changes in offspring. Epigenetic inheritance requires epigenetic changes (i.e. epimutations) in germ cells that promote epigenetic and gene expression changes in embryos. The objective of this perspective is to examine the evidence that germ cell epigenome modifications are associated with embryo cell epigenetic and transcriptome changes that affect the subsequent development of all developing somatic cells to promote phenotype change. Various epigenetic changes in sperm, including changes to histone methylation, histone retention, non-coding RNA expression and DNA methylation, have been associated with alterations in embryo cell epigenetics and gene expression. Few studies have investigated this link for oocytes. The studies reviewed herein support the idea that environmentally induced epigenetic changes in germ cells affect alterations in embryo cell epigenetics and transcriptomes that have an important role in the epigenetic inheritance of pathology and phenotypic change.

scholarly journals Symposium summary: Epigenetic inheritance—impact for biology and society 26–28 August 2019, Zurich, Switzerland

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Irina Lazar-Contes ◽  
Martin Roszkowski ◽  
Deepak K Tanwar ◽  
Isabelle M Mansuy
Keyword(s):  
Functional Genomics ◽  
Dna Sequence ◽  
Germ Cells ◽  
Paradigm Shift ◽  
Epigenetic Inheritance ◽  
Epigenetic Changes ◽  
Epigenetic Factors ◽  
Nature Versus Nurture ◽  
Poster Sessions ◽  
Health And Disease

Abstract The concept of epigenetic inheritance proposes a new and unconventional way to think about heredity in health and disease, at the interface between genetics and the environment. Epigenetic inheritance is a form of biological inheritance not encoded in the DNA sequence itself but mediated by epigenetic factors. Because epigenetic factors can be modulated by the environment, they can relay this information to the genome and modify its activity consequentially. If epigenetic changes induced by environmental exposure are present in the germline and persist in germ cells during development until conception, they have the potential to transfer the traces of ancestral exposure to the progeny. This form of heredity relates to the extremely important question of nature versus nurture and how much of our own make-up is genetically or epigenetically determined, a question that remains largely unresolved. Because it questions the dominant dogma of genetics and brings a paradigm shift in sciences, it has to creating strong bridges between disciplines and provide solid causal evidence to be firmly established. The second edition of a conference fully dedicated to epigenetic inheritance was held in August 2019 in Zurich, Switzerland. This symposium titled ‘Epigenetic inheritance: impact for biology and society’ (http://www.epigenetic-inheritance-zurich.ethz.ch), gathered experts in the field of epigenetic inheritance to discuss the concept and pertinent findings, exchange views and expertise about models and methods, and address challenges raised by this new discipline. The symposium offered a mix of invited lectures and short talks selected from abstracts, poster sessions and a workshop ‘Meet the experts: Q&A’. A tour of a local omics facility the Functional Genomics Center Zurich was also offered to interested participants. Additional comments and impressions were shared by attendees on Twitter #eisz19 during and after the symposium. This summary provides an overview of the different sessions and talks and describes the main findings presented.

scholarly journals A Study on the Serial Position Effect of Memory according to Illumination of LED Light

2019 ◽  
Vol 120 ◽  
pp. 01002
Author(s):  
Chung Won Lee ◽  
Jin Ho Kim ◽  
In Keuk Hwang
Keyword(s):  
Cognitive Impairment ◽  
Serial Position ◽  
Serial Position Effect ◽  
Position Effect ◽  
Memory Task ◽  
Word List ◽  
Memory Retention ◽  
Position Effects ◽  
Serial Position Effects ◽  
Significant Difference

The purpose of this study was to verify the forms of the effect of serial position effects of memory according to the illuminance of light. This study was conducted as an experimental method, and 21 adults without cognitive impairment participated in the study. The illuminance condition was designed with high illuminance condition of 1,000 lx and low illuminance condition of 300 lx. The memory task used word list of 20 items consisting of a series of pointless spellings. After memorizing the word list for 10 minutes, the participant performed a retention task 24 hours later. The memory retention task consisted of filling the empty part of the learned word and completing the word. The analysis was performed by dividing the word items into three conditions: primacy, middle, and recency. Primacy used the first item in the word list, Middle used the 10th item in the middle of the word list, and finally Recency used the last item in the word list for analysis. The result was F = 4.16 (p = .02), and showed that there was a statistically significant difference in memory retention of primacy, middle, and recency at 95% confidence level in dim condition.

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