http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Tue, 19 Feb 2013 11:22:46 +0000 http://www.hindawi.com/journals/gri/2013/852080/ Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by homozygous expansion of a GAA·TTC trinucleotide repeat within the first intron of the FXN gene, leading to reduced FXN transcription and decreased levels of frataxin protein. Recent advances in FRDA research have revealed the presence of several epigenetic modifications that are either directly or indirectly involved in this FXN gene silencing. Although epigenetic marks may be inherited from one generation to the next, modifications of DNA and histones can be reversed, indicating that they are suitable targets for epigenetic-based therapy. Unlike other trinucleotide repeat disorders, such as Huntington disease, the large expansions of GAA·TTC repeats in FRDA do not produce a change in the frataxin amino acid sequence, but they produce reduced levels of normal frataxin. Therefore, transcriptional reactivation of the FXN gene provides a good therapeutic option. The present paper will initially focus on the epigenetic changes seen in FRDA patients and their role in the silencing of FXN gene and will be concluded by considering the potential epigenetic therapies. Chiranjeevi Sandi, Sahar Al-Mahdawi, and Mark A. Pook Copyright © 2013 Chiranjeevi Sandi et al. All rights reserved. Wed, 05 Dec 2012 13:34:31 +0000 http://www.hindawi.com/journals/gri/2012/129575/ The aim of the study was to report a description of the primary, secondary, and tertiary level services available for genetic disorders in Iran. For the purpose of this study, essential data were collected from every facility providing community genetic services in Tabriz city of Iran using a prestructured checklist. Technical information was filled in the predesigned forms using diagnostic records of each client/patient. Information was also gathered from community genetic services clients through a face-to-face interview at these facilities to assess the quality of services provided. Primary prevention measures were available in 80 percent of centres in the study population. Diagnostic techniques were fully available in the study area both in public and private sectors. Screening of congenital hypothyroidism and thalassemia has been successfully performed across the country by the Ministry of Health. Other screening programs have also been initiated by the country health authorities for neural tube defects, Down syndrome, and phenylketonuria. The high cost of genetic services at secondary and tertiary levels does not allow many people to get access to these services despite their needs. Governments will therefore need to allocate necessary resources to make the essential genetic services available for everyone needing these in the community. Shirin Atri Barzanjeh, Mozhgan Behshid, Mohammad Bagher Hosseini, Maryam Ezari, Mahdieh Taghizadeh, and Saeed Dastgiri Copyright © 2012 Shirin Atri Barzanjeh et al. All rights reserved. Tue, 04 Dec 2012 14:32:58 +0000 http://www.hindawi.com/journals/gri/2012/748698/ The inner ear cytoarchitecture forms one of the most intricate and delicate organs in the human body and is vulnerable to the effects of genetic disorders, aging, and environmental damage. Owing to the inability of the mammalian cochlea to regenerate sensory hair cells, the loss of hair cells is a leading cause of deafness in humans. Millions of individuals worldwide are affected by the emotionally and financially devastating effects of hearing impairment (HI). This paper provides a brief introduction into the key role of genes regulating inner ear development and function. Potential future therapies that leverage on an improved understanding of these molecular pathways are also described in detail. Joel Sng and Thomas Lufkin Copyright © 2012 Joel Sng and Thomas Lufkin. All rights reserved. Wed, 28 Nov 2012 15:43:36 +0000 http://www.hindawi.com/journals/gri/2012/491204/ Vett K. Lloyd, Jennifer A. Brisson, Kathleen A. Fitzpatrick, Lori A. McEachern, and Eveline C. Verhulst Copyright © 2012 Vett K. Lloyd et al. All rights reserved. Wed, 18 Jul 2012 14:15:04 +0000 http://www.hindawi.com/journals/gri/2012/737416/ Lung cancer biology has traditionally focused on genomic and epigenomic deregulation of protein-coding genes to identify oncogenes and tumor suppressors diagnostic and therapeutic targets. Another important layer of cancer biology has emerged in the form of noncoding RNAs (ncRNAs), which are major regulators of key cellular processes such as proliferation, RNA splicing, gene regulation, and apoptosis. In the past decade, microRNAs (miRNAs) have moved to the forefront of ncRNA cancer research, while the role of long noncoding RNAs (lncRNAs) is emerging. Here we review the mechanisms by which miRNAs and lncRNAs are deregulated in lung cancer, the technologies that can be applied to detect such alterations, and the clinical potential of these RNA species. An improved comprehension of lung cancer biology will come through the understanding of the interplay between deregulation of non-coding RNAs, the protein-coding genes they regulate, and how these interactions influence cellular networks and signalling pathways. Katey S. S. Enfield, Larissa A. Pikor, Victor D. Martinez, and Wan L. Lam Copyright © 2012 Katey S. S. Enfield et al. All rights reserved. Sun, 10 Jun 2012 15:25:43 +0000 http://www.hindawi.com/journals/gri/2012/648207/ The Notch signaling pathway is an evolutionarily conserved intercellular signaling mechanism that is required for embryonic development, cell fate specification, and stem cell maintenance. Discovered and studied initially in Drosophila melanogaster, the Notch pathway is conserved and functionally active throughout the animal kingdom. In this paper, we summarize the biochemical mechanisms of Notch signaling and describe its role in regulating one particular developmental pathway, oogenesis in Drosophila. Jingxia Xu and Thomas Gridley Copyright © 2012 Jingxia Xu and Thomas Gridley. All rights reserved. Wed, 18 Apr 2012 11:57:32 +0000 http://www.hindawi.com/journals/gri/2012/562848/ Edi Lúcia Sartorato, Karen Friderici, and Ignacio Del Castillo Copyright © 2012 Edi Lúcia Sartorato et al. All rights reserved. Sun, 08 Apr 2012 12:39:15 +0000 http://www.hindawi.com/journals/gri/2012/867390/ Recently, epigenetics has had an ever-growing impact on research not only for its intrinsic interest but also because it has been implied in biological phenomena, such as tumor emergence and progression. The first epigenetic phenomenon to be described in the early 1960s was chromosome imprinting in some insect species (sciaridae and coccoideae). Here, we discuss recent experimental results to dissect the phenomenon of imprinted facultative heterochromatinization in Lecanoid coccids (mealybugs). In these insect species, the entire paternally derived haploid chromosome set becomes heterochromatic during embryogenesis in males. We describe the role of known epigenetic marks, such as DNA methylation and histone modifications, in this phenomenon. We then discuss the models proposed to explain the noncanonical chromosome cycle of these species. Giorgio Prantera and Silvia Bongiorni Copyright © 2012 Giorgio Prantera and Silvia Bongiorni. All rights reserved. Wed, 04 Apr 2012 11:35:46 +0000 http://www.hindawi.com/journals/gri/2012/174860/ Daphnids are fresh water microcrustaceans, many of which follow a cyclically parthenogenetic life cycle. Daphnia species have been well studied in the context of ecology, toxicology, and evolution, but their epigenetics remain largely unexamined even though sex determination, the production of sexual females and males, and distinct adult morphological phenotypes, are determined epigenetically. Here, we report on the characterization of histone modifications in Daphnia. We show that a number of histone H3 and H4 modifications are present in Daphnia embryos and histone H3 dimethylated at lysine 4 (H3K4me2) is present nonuniformly in the nucleus in a cell cycle-dependent manner. In addition, this histone modification, while present in blastula and gastrula cells as well as the somatic cells of adults, is absent or reduced in oocytes and nurse cells. Thus, the epigenetic repertoire of Daphnia includes modified histones and as these epigenetic forces act on a genetically homogeneous clonal population Daphnia offers an exceptional tool to investigate the mechanism and role of epigenetics in the life cycle and development of an ecologically important species. Nicole F. Robichaud, Jeanette Sassine, Margaret J. Beaton, and Vett K. Lloyd Copyright © 2012 Nicole F. Robichaud et al. All rights reserved. Wed, 28 Mar 2012 14:26:36 +0000 http://www.hindawi.com/journals/gri/2012/609810/ Epigenetic modifications to DNA, such as DNA methylation, can expand a genome’s regulatory flexibility, and thus may contribute to the evolution of phenotypic plasticity. Recent work has demonstrated the importance of DNA methylation in alternative queen and worker “castes” in social insects, particularly honeybees. Social insects are an excellent system for addressing questions about epigenetics and evolution because: (1) they have dramatic caste polyphenisms that appear to be tied to differential methylation, (2) DNA methylation is widespread in various groups of social insects, and (3) there are intriguing connections between the social environment and DNA methylation in many species, from insects to mammals. In this article, we review research on honeybees, and, when available, other social insects, on DNA methylation and queen and worker caste differences. We outline a conceptual framework for the effects of methylation on caste determination in honeybees that may help guide studies of epigenetic regulation in other polyphenic taxa. Finally, we suggest future paths of study for social insect epigenetic research, including the importance of comparative studies of DNA methylation on a broader range of species, and highlight some key unanswered mechanistic questions about how DNA methylation affects gene regulation. Susan A. Weiner and Amy L. Toth Copyright © 2012 Susan A. Weiner and Amy L. Toth. All rights reserved. Tue, 27 Mar 2012 14:48:20 +0000 http://www.hindawi.com/journals/gri/2012/689819/ Non-model organisms are generally more difficult and/or time consuming to work with than model organisms. In addition, epigenetic analysis of model organisms is facilitated by well-established protocols, and commercially-available reagents and kits that may not be available for, or previously tested on, non-model organisms. Given the evolutionary conservation and widespread nature of many epigenetic mechanisms, a powerful method to analyze epigenetic phenomena from non-model organisms would be to use transgenic model organisms containing an epigenetic region of interest from the non-model. Interestingly, while transgenic Drosophila and mice have provided significant insight into the molecular mechanisms and evolutionary conservation of the epigenetic processes that target epigenetic control regions in other model organisms, this method has so far been under-exploited for non-model organism epigenetic analysis. This paper details several experiments that have examined the epigenetic processes of genomic imprinting and paramutation, by transferring an epigenetic control region from one model organism to another. These cross-species experiments demonstrate that valuable insight into both the molecular mechanisms and evolutionary conservation of epigenetic processes may be obtained via transgenic experiments, which can then be used to guide further investigations and experiments in the species of interest. Lori A. McEachern Copyright © 2012 Lori A. McEachern. All rights reserved. Sun, 25 Mar 2012 13:48:23 +0000 http://www.hindawi.com/journals/gri/2012/758384/ Sebastián Chávez, David S. Gross, Damien Hermand, and Carlos Suñé Copyright © 2012 Sebastián Chávez et al. All rights reserved. Wed, 21 Mar 2012 16:11:07 +0000 http://www.hindawi.com/journals/gri/2012/431531/ Environmental conditions can alter the form, function, and behavior of organisms over short and long timescales, and even over generations. Aphid females respond to specific environmental cues by transmitting signals that have the effect of altering the development of their offspring. These epigenetic phenomena have positioned aphids as a model for the study of phenotypic plasticity. The molecular basis for this epigenetic inheritance in aphids and how this type of inheritance system could have evolved are still unanswered questions. With the availability of the pea aphid genome sequence, new genomics technologies, and ongoing genomics projects in aphids, these questions can now be addressed. Here, we review epigenetic phenomena in aphids and recent progress toward elucidating the molecular basis of epigenetics in aphids. The discovery of a functional DNA methylation system, functional small RNA system, and expanded set of chromatin modifying genes provides a platform for analyzing these pathways in the context of aphid plasticity. With these tools and further research, aphids are an emerging model system for studying the molecular epigenetics of polyphenisms. Dayalan G. Srinivasan and Jennifer A. Brisson Copyright © 2012 Dayalan G. Srinivasan and Jennifer A. Brisson. All rights reserved. Sun, 18 Mar 2012 10:13:39 +0000 http://www.hindawi.com/journals/gri/2012/845429/ The molecular players of circadian clock oscillation have been identified and extensively characterized. The epigenetic mechanisms behind the circadian gene expression control has also been recently studied, although there are still details to be illucidated. In this review, we briefly summarize the current understanding of the mammalian clock. We also provide evidence for the lack of circadian oscillation in particular cell types. As the circadian clock has intimate interaction with the various cellular functions in different type of cells, it must have plasticity and specicity in its operation within different epigenetic environments. The lack of circadian oscillation in certain cells provide an unique opportunity to study the required epigenetic environment in the cell that permit circadian oscillation and to idenfify key influencing factors for proper clock function. How epigenetic mechansims, including DNA methylaiton and chromatin modifications, participate in control of clock oscillation still awaits future studies at the genomic scale. Chengwei Li, Changxia Gong, Shuang Yu, Jianguo Wu, and Xiaodong Li Copyright © 2012 Chengwei Li et al. All rights reserved. Wed, 07 Mar 2012 08:19:15 +0000 http://www.hindawi.com/journals/gri/2012/179159/ Deer mice (Peromyscus) offer an opportunity for studying the effects of natural genetic/epigenetic variation with several advantages over other mammalian models. These advantages include the ability to study natural genetic variation and behaviors not present in other models. Moreover, their life histories in diverse habitats are well studied. Peromyscus resources include genome sequencing in progress, a nascent genetic map, and >90,000 ESTs. Here we review epigenetic studies and relevant areas of research involving Peromyscus models. These include differences in epigenetic control between species and substance effects on behavior. We also present new data on the epigenetic effects of diet on coat-color using a Peromyscus model of agouti overexpression. We suggest that in terms of tying natural genetic variants with environmental effects in producing specific epigenetic effects, Peromyscus models have a great potential. Kimberly R. Shorter, Janet P. Crossland, Denessia Webb, Gabor Szalai, Michael R. Felder, and Paul B. Vrana Copyright © 2012 Kimberly R. Shorter et al. All rights reserved. Tue, 06 Mar 2012 11:19:02 +0000 http://www.hindawi.com/journals/gri/2012/543286/ Diarrheic food poisoning by bacteria of the Bacillus cereus group is mostly due to several toxins encoded in the genomes. One of them, cytotoxin K, was recently identified as responsible for severe necrotic syndromes. Cytotoxin K is similar to a class of proteins encoded by genes usually annotated as haemolysin II (hlyII) in the majority of genomes of the B. cereus group. The partially sequenced genome of Bacillus thuringiensis var israelensis ATCC35646 contains several potentially induced prophages, one of them integrated into the hlyII gene. We determined the complete sequence and established the genomic organization of this prophage-designated phIS3501. During induction of excision of this prophage with mitomycin C, intact hlyII gene is formed, thus providing to cells a genetic ability to synthesize the active toxin. Therefore, this prophage, upon its excision, can be implicated in the regulation of synthesis of the active toxin and thus in the virulence of bacterial host. A generality of selection for such systems in bacterial pathogens is indicated by the similarity of this genetic arrangement to that of Staphylococcus aureus  𝛽-haemolysin. Bouziane Moumen, Christophe Nguen-The, and Alexei Sorokin Copyright © 2012 Bouziane Moumen et al. All rights reserved. Mon, 05 Mar 2012 10:49:49 +0000 http://www.hindawi.com/journals/gri/2012/576303/ All developmental plasticity arises through epigenetic mechanisms. In this paper we focus on the nature, origins, and consequences of these mechanisms with a focus on horned beetles, an emerging model system in evolutionary developmental genetics. Specifically, we introduce the biological significance of developmental plasticity and summarize the most important facets of horned beetle biology. We then compare and contrast the epigenetic regulation of plasticity in horned beetles to that of other organisms and discuss how epigenetic mechanisms have facilitated innovation and diversification within and among taxa. We close by highlighting opportunities for future studies on the epigenetic regulation of plastic development in these and other organisms. Sophie Valena and Armin P. Moczek Copyright © 2012 Sophie Valena and Armin P. Moczek. All rights reserved. Mon, 05 Mar 2012 10:32:25 +0000 http://www.hindawi.com/journals/gri/2012/286164/ Aaron W. Schrey, Christina L. Richards, Victoria Meller, Vincent Sollars, and Douglas M. Ruden Copyright © 2012 Aaron W. Schrey et al. All rights reserved. Sun, 04 Mar 2012 09:05:49 +0000 http://www.hindawi.com/journals/gri/2012/698421/ The dualism of genetic predisposition and environmental influences, their interactions, and respective roles in shaping the phenotype have been a hot topic in biological sciences for more than two centuries. Heritable epigenetic variation mediates between relatively slowly accumulating mutations in the DNA sequence and ephemeral adaptive responses to stress, thereby providing mechanisms for achieving stable, but potentially rapidly evolving phenotypic diversity as a response to environmental stimuli. This suggests that heritable epigenetic signals can play an important role in evolutionary processes, but so far this hypothesis has not been rigorously tested. A promising new area of research focuses on the interaction between the different molecular levels that produce phenotypic variation in wild, closely-related taxa that lack genome-wide genetic differentiation. By pinpointing specific adaptive traits and investigating the mechanisms responsible for phenotypic differentiation, such study systems could allow profound insights into the role of epigenetics in the evolution and stabilization of phenotypic discontinuities, and could add to our understanding of adaptive strategies to diverse environmental conditions and their dynamics. Ruth Flatscher, Božo Frajman, Peter Schönswetter, and Ovidiu Paun Copyright © 2012 Ruth Flatscher et al. All rights reserved. Sun, 26 Feb 2012 13:53:37 +0000 http://www.hindawi.com/journals/gri/2011/835053/ José María Sayagués, Sergio Roa, Norma C. Gutierrez, and Ilana Zalcberg Renault Copyright © 2011 José María Sayagués et al. All rights reserved. Sun, 26 Feb 2012 08:10:28 +0000 http://www.hindawi.com/journals/gri/2012/347214/ The C-terminal domain (CTD) of RNA polymerase II (Pol II) consists of conserved heptapeptide repeats that function as a binding platform for different protein complexes involved in transcription, RNA processing, export, and chromatin remodeling. The CTD repeats are subject to sequential waves of posttranslational modifications during specific stages of the transcription cycle. These patterned modifications have led to the postulation of the “CTD code” hypothesis, where stage-specific patterns define a spatiotemporal code that is recognized by the appropriate interacting partners. Here, we highlight the role of CTD modifications in directing transcription initiation, elongation, and termination. We examine the major readers, writers, and erasers of the CTD code and examine the relevance of describing patterns of posttranslational modifications as a “code.” Finally, we discuss major questions regarding the function of the newly discovered CTD modifications and the fundamental insights into transcription regulation that will necessarily emerge upon addressing those challenges. David W. Zhang, Juan B. Rodríguez-Molina, Joshua R. Tietjen, Corey M. Nemec, and Aseem Z. Ansari Copyright © 2012 David W. Zhang et al. All rights reserved. Thu, 23 Feb 2012 12:57:10 +0000 http://www.hindawi.com/journals/gri/2012/946032/ Autonomy takes many shapes. The concept of “graduated autonomy” is conceived as comprising several unique features: (1) it is incremental, (2) it is proportional, and (3) it is related to the telos of the life stage during which it occurs. This paper focuses on graduated autonomy in the context of genetic testing during adolescence. Questions can be raised about other life stages as well, and some of these questions will be addressed by discussing a possible fourth characteristic of graduated autonomy, that is, its elasticity. Further scholarship and analysis is needed to refine the concept of graduated autonomy and examine its applications. Susan Fox Copyright © 2012 Susan Fox. All rights reserved. Tue, 21 Feb 2012 14:47:39 +0000 http://www.hindawi.com/journals/gri/2012/786930/ Genetic testing in children raises many important ethical, legal, and social issues. One of the main concerns is the ethically inappropriate genetic testing of minors. Various European countries established professional guidelines which reflect the different countries perspectives regarding the main ethical issues involved. In this paper, we analyze the Italian and the British guidelines by highlighting differences and similarities. We discuss presymptomatic, predictive, and carrier testing because we consider them to be the more ethically problematic types of genetic testing in minors. In our opinion, national guidelines should take into account the different needs in clinical practice. At the same time, in the case of genetic testing the national and supranational protection of minors could be strengthened by approving guidelines based on a common framework of principles and values. We suggest that the Oviedo Convention could represent an example of such a common framework or, at least, it could lead to articulate it. Pamela Tozzo, Luciana Caenazzo, and Daniele Rodriguez Copyright © 2012 Pamela Tozzo et al. All rights reserved. Mon, 20 Feb 2012 12:26:33 +0000 http://www.hindawi.com/journals/gri/2012/287432/ Hearing impairment is common in patients with mitochondrial disorders, affecting over half of all cases at some time in the course of the disease. In some patients, deafness is only part of a multisystem disorder. By contrast, there are also a number of “pure” mitochondrial deafness disorders, the most common probably being maternally inherited. We retrospectively analyzed the last 60 genetically confirmed mitochondrial disorders diagnosed in our Department: 28 had bilateral sensorineural hearing loss, whereas 32 didn't present ear's abnormalities, without difference about sex and age of onset between each single group of diseases. We reported also a case of MELAS patient with sensorineural hearing loss, in which cochlear implantation greatly contributed to the patient's quality of life. Our study suggests that sensorineural hearing loss is an important feature in mitochondrial disorders and indicated that cochlear implantation can be recommended for patients with MELAS syndrome and others mitochondrial disorders. Mauro Scarpelli, Francesca Zappini, Massimiliano Filosto, Anna Russignan, Paola Tonin, and Giuliano Tomelleri Copyright © 2012 Mauro Scarpelli et al. All rights reserved. Mon, 20 Feb 2012 11:16:43 +0000 http://www.hindawi.com/journals/gri/2012/856157/ Hearing loss is the most common symptom in patients with vestibular schwannoma (VS). In the past, compressive mechanisms caused by the tumoral mass and its growth have been regarded as the most likely causes of the hearing loss associated with VS. Interestingly, new evidence proposes molecular mechanisms as an explanation for such hearing loss. Among the molecular mechanisms proposed are methylation of TP73, negative expression of cyclin D1, expression of B7-H1, increased expression of the platelet-derived growth factor A, underexpression of PEX5L, RAD54B, and PSMAL, and overexpression of CEA. Many molecular mechanisms are involved in vestibular schwannoma development; we review some of these mechanisms with special emphasis on hearing loss associated with vestibular schwannoma. Erika Celis-Aguilar, Luis Lassaletta, Miguel Torres-Martín, F. Yuri Rodrigues, Manuel Nistal, Javier S. Castresana, Javier Gavilan, and Juan A. Rey Copyright © 2012 Erika Celis-Aguilar et al. All rights reserved. Sun, 19 Feb 2012 15:21:45 +0000 http://www.hindawi.com/journals/gri/2012/392903/ Histone modifications are widely recognized for their fundamental importance in regulating gene expression in embryonic development in a wide range of eukaryotes, but they have received relatively little attention in the development of marine invertebrates. We surveyed histone modifications throughout the development of a marine annelid, Polydora cornuta, to determine if modifications could be detected immunohistochemically and if there were characteristic changes in modifications throughout ontogeny (surveyed at representative stages from oocyte to adult). We found a common time of onset for three histone modifications in early cleavage (H3K14ac, H3K9me, and H3K4me2), some differences in the distribution of modifications among germ layers, differences in epifluorescence intensity in specific cell lineages suggesting that hyperacetylation (H3K14ac) and hypermethylation (H3K9me) occur during differentiation, and an overall decrease in the distribution of modifications from larvae to adults. Although preliminary, these results suggest that histone modifications are involved in activating early development and differentiation in a marine invertebrate. Glenys Gibson, Corban Hart, Robyn Pierce, and Vett Lloyd Copyright © 2012 Glenys Gibson et al. All rights reserved. Wed, 15 Feb 2012 15:47:14 +0000 http://www.hindawi.com/journals/gri/2012/585024/ Genomic imprinting is a form of epigenetic inheritance whereby the regulation of a gene or chromosomal region is dependent on the sex of the transmitting parent. During gametogenesis, imprinted regions of DNA are differentially marked in accordance to the sex of the parent, resulting in parent-specific expression. While mice are the primary research model used to study genomic imprinting, imprinted regions have been described in a broad variety of organisms, including other mammals, plants, and insects. Each of these organisms employs multiple, interrelated, epigenetic mechanisms to maintain parent-specific expression. While imprinted genes and imprint control regions are often species and locus-specific, the same suites of epigenetic mechanisms are often used to achieve imprinted expression. This review examines some examples of the epigenetic mechanisms responsible for genomic imprinting in mammals, plants, and insects. William A. MacDonald Copyright © 2012 William A. MacDonald. All rights reserved. Tue, 14 Feb 2012 11:24:30 +0000 http://www.hindawi.com/journals/gri/2012/534289/ Asexual organisms, often perceived as evolutionary dead ends, can be long-lived and geographically widespread. We propose that epigenetic mechanisms could play a crucial role in the evolutionary persistence of these lineages. Genetically identical organisms could rely on phenotypic plasticity to face environmental variation. Epigenetic modifications could be the molecular mechanism enabling such phenotypic plasticity; they can be influenced by the environment and act at shorter timescales than mutation. Recent work on the asexual vertebrate Chrosomus eos-neogaeus (Pisces: Cyprinidae) provides broad insights into the contribution of epigenetics in genetically identical individuals. We discuss the extension of these results to other asexual organisms, in particular those resulting from interspecific hybridizations. We finally develop on the evolutionary relevance of epigenetic variation in the context of heritability. Emilie Castonguay and Bernard Angers Copyright © 2012 Emilie Castonguay and Bernard Angers. All rights reserved. Thu, 09 Feb 2012 10:05:52 +0000 http://www.hindawi.com/journals/gri/2012/979751/ Epigenetic mechanisms impact several phenotypic traits and may be important for ecology and evolution. The introduced house sparrow (Passer domesticus) exhibits extensive phenotypic variation among and within populations. We screened methylation in populations from Kenya and Florida to determine if methylation varied among populations, varied with introduction history (Kenyan invasion <50 years old, Florida invasion ~150 years old), and could potentially compensate for decrease genetic variation with introductions. While recent literature has speculated on the importance of epigenetic effects for biological invasions, this is the first such study among wild vertebrates. Methylation was more frequent in Nairobi, and outlier loci suggest that populations may be differentiated. Methylation diversity was similar between populations, in spite of known lower genetic diversity in Nairobi, which suggests that epigenetic variation may compensate for decreased genetic diversity as a source of phenotypic variation during introduction. Our results suggest that methylation differences may be common among house sparrows, but research is needed to discern whether methylation impacts phenotypic variation. Aaron W. Schrey, Courtney A. C. Coon, Michael T. Grispo, Mohammed Awad, Titus Imboma, Earl D. McCoy, Henry R. Mushinsky, Christina L. Richards, and Lynn B. Martin Copyright © 2012 Aaron W. Schrey et al. All rights reserved. Sun, 29 Jan 2012 10:59:46 +0000 http://www.hindawi.com/journals/gri/2012/430136/ Satellites are one of the most enigmatic parts of the eukaryotic genome. These highly repetitive, noncoding sequences make up as much as half or more of the genomic content and are known to play essential roles in chromosome segregation during meiosis and mitosis, yet they evolve rapidly between closely related species. Research over the last several decades has revealed that satellite divergence can serve as a formidable reproductive barrier between sibling species. Here we highlight several key studies on Drosophila and other model organisms demonstrating deleterious effects of satellites and their rapid evolution on the structure and function of chromosomes in interspecies hybrids. These studies demonstrate that satellites can impact chromosomes at a number of different developmental stages and through distinct cellular mechanisms, including heterochromatin formation. These findings have important implications for how loci that cause postzygotic reproductive isolation are viewed. Patrick M. Ferree and Satyaki Prasad Copyright © 2012 Patrick M. Ferree and Satyaki Prasad. All rights reserved.