O presente estudo teve como objetivo avaliar e comparar os processos de polpação sodaantraquinona e bissulfito base magnésio para Bambusa vulgaris Schrad. com 2 anos de idade oriundos de plantios comerciais no Maranhão Brasil visando a produção de polpa celulósica branqueável e não branqueável (números kappa 30±2 e 50±2 respectivamente). A matéria-prima foi caracterizada com relação à densidade básica, composição química e dimensões de fibras; para aos processos de polpação avaliou-se o tempo total de cozimento, o fator H, o rendimento bruto, rendimento depurado, teor de rejeitos, carga de reagentes químicos e propriedades físicomecânicas das polpas. Os resultados obtidos mostram que a matéria-prima apresentou valores típicos para a espécie em questão no que diz respeito à densidade básica, dimensões e índices morfológicos das fibras e composição química. Para o processo de polpação soda-antraquinona os níveis de deslignificação determinados (números kappa) foram obtidos com cargas alcalinas de 15 e 19% (base NaOH) respectivamente e fator H de 1218; para o processo bissulfito base magnésio as polpas celulósicas com os níveis de deslignificação estabelecidos foram obtidas com uma mesma carga de reagentes químicos 26% (base SO2) e fator H de 1218 para polpas com número kappa 30±2 e 828 para polpas com número kappa 50±2; o tempo total de cozimento para o processo soda-antraquinona necessário para obtenção das polpas celulósicas desejadas são, em média, 3,8 vezes menores aos do processo bissulfito base magnésio. Adicionalmente os rendimentos depurados foram 3,0 e 4,6 pontos porcentuais superiores para as polpas com números kappa 30±2 e 50±2 respectivamente no processo soda-antraquinona. Os ensaios físicomecânicos mostram as diferenças entre as polpas tanto no que diz respeito ao processo de polpação empregado quanto no nível de deslignificação, sendo este último um fator de diferenciação dos produtos (papel) que podem ser obtidos a partir das polpas celulósicas. Comparando-se os processos de polpação no que diz respeito às propriedades físico-mecânicas observa-se a superioridade das polpas soda-antraquinona exceto nos parâmetros de drenabilidade e densidade aparente. Os resultados obtidos neste trabalho mostram que para a produção de polpa celulósica a partir de Bambusa vulgaris o processo soda-antraquinona é superior ao processo bissulfito base magnésio tanto nos aspectos de engenharia de processo (quantitativos) como nos aspectos relacionados à qualidade da polpa obtida. / The present study had as objective evaluates and to compare the soda-antraquinone and magnesium base bisulfite pulping processes for Bambusa vulgaris Schrad. with 2 years old originating from commercial plantings in Maranhão Brazil seeking the production of bleachable and unbleachable cellulosic pulp grade\'s (kappa numbers 30±2 and 50±2 respectively). The raw material was characterized regarding the basic density, chemical composition and dimensions of fibers; for to the pulping processes was evaluated the total time of cooking, H factor, total yield, screened yield, rejects, load of chemical reagents and physicalmechanical properties of the pulps. The obtained results show that the raw material presented typical values for the species in subject in what says respect to the basic density, dimensions and morphologic indexes of the fibers and chemical composition. For the soda-antraquinone pulping process the certain levels of delignification (kappa numbers) were obtained with alkaline loads of 15 and 19% (NaOH base) respectively and a H factor of 1218; for the magnesium base bisulfite process the cellulosic pulps with the established levels of delignification were obtained with a fix load of chemical reagents 26% (SO2 base) and H factor of 1218 for pulps with kappa number 30±2 and 828 for pulps with kappa number 50±2; the necessary total time of cooking to the sodaantraquinone process to obtain the wanted cellulosic pulps are, on average, 3,82 time less when compared with the bisulfite process. Additionally the screened yields were 3 and 4,63 percent superior for the pulps with numbers kappa 30±2 and 50±2 respectively in the soda-antraquinone process. The physical-mechanical tests show the differences among the pulps in what says respect to the used pulping process as in the delignification level, being this last one a factor of differentiation of the products (paper) that can be obtained starting from the cellulosic pulps. Comparing the pulping processes as what concerns of physical-mechanical properties the superiority of the soda-antraquinone pulps is observed except in freeness and density parameters. The results obtained in this work show that for the production of cellulosic pulp from Bambusa vulgaris the soda-antraquinone process it is superior than the magnesium base bisulfite process as much in the aspects of engineering process (quantitative) as in the aspects related to the quality of the obtained pulp.

This master's thesis deals with the creation of a tool for the extraction of methylation level from transposon sequences. Transposons are DNA elements with ability to move or copy themselves and their activity is regulated by DNA methylation. Sequence methylation information is stored in the bisulfite data and their processing is done with parts of two existing tools in a combination with implemented modules. Created tool takes into consideration unique challenges brought in the methylation calling process by transposable elements and it's functionality is presented on a set of experiments with simulated and real data.

No description available.

Polyploidization instantly doubles all genome content by combining two genomes that have markedly different methylation and gene expression levels. This process may be accompanied by genetic and epigenetic changes in each genome. Sequencing of the transcriptome (RNA-seq) and the methylome (bisulfite treated libraries whole genome libraries) were used to measure gene expression and methylation levels of genic regions of allopolyploid cotton petals and petals of their diploid relatives. Many differentially expressed genes detected by RNA-seq were consistent with expression levels previously detected by microarrays. RNA-seq results also reconfirmed the presence of general polyploid gene expression trends like expression level dominance and homoeologous expression biases in Gossypium polyploid species. Expression biases between A- and D-genome homoeologs and expression level dominance was characterized for thousands of genes in tetraploids and a diploid F1-hybrid. Unlike the results of microarray study previously done we found a slightly greater number of genes showing A-genome bias vs genes showing D-genome bias. More commonly the overall expression level from homoeologs of polyploid is heterotic i.e the expression level is greater than the average of the expression levels from the two parent genomes. In addition, genome methylation (CG, CHG, and CHH contexts) of each genome was assessed in the diploid and tetraploid samples. The A- and D-genomes had distinct levels of DNA methylation for each context. DNA methylation may be independently regulating homoeologous expression levels of a small number of genes.

Weed resistance to control measures, particularly herbicides, is a growing problem in agriculture. In the case of herbicides, resistance is sometimes connected to genetic changes that directly affect the target site of the herbicide. Other cases are less straightforward where resistance arises without such a clear-cut mechanism. Understanding the genetic and gene regulatory mechanisms that may lead to the rapid evolution of resistance in weedy species is critical to securing our food supply. To study this phenomenon, we exposed young Arabidopsis plants to sublethal levels of one of four weed management stressors, glyphosate herbicide, trifloxysulfuron herbicide, mechanical clipping, and shading. To evaluate responses to these stressors we collected data on gene expression and regulation via epigenetic modification (methylation) and small RNA (sRNA). For all of the treatments except shade, the stress was limited in duration, and the plants were allowed to recover until flowering, to identify changes that persist to reproduction. At flowering, DNA for methylation bisulfite sequencing, RNA, and sRNA were extracted from newly formed rosette leaf tissue. Analyzing the individual datasets revealed many differential responses when compared to the untreated control for gene expression, methylation, and sRNA expression. All three measures showed increases in differential abundance that were unique to each stressor, with very little overlap between stressors. Herbicide treatments tended to exhibit the largest number of significant differential responses, with glyphosate treatment most often associated with the greatest differences and contributing to overlap. To evaluate how large datasets from methylation, gene expression, and sRNA analyses could be connected and mined to link regulatory information with changes in gene expression, the information from each dataset and for each gene was united in a single large matrix and mined with classification algorithms. Although our models were able to differentiate patterns in a set of simulated data, the raw datasets were too noisy for the models to consistently identify differentially expressed genes. However, by focusing on responses at a local level, we identified several genes with differential expression, differential sRNA, and differential methylation. While further studies will be needed to determine whether these epigenetic changes truly influence gene expression at these sites, the changes detected at the treatment level could prime the plants for future incidents of stress, including herbicides. / Doctor of Philosophy / Growing resistance to herbicides, particularly glyphosate, is one of the many problems facing agriculture. The rapid rise of resistance across herbicide classes has caused some to wonder if there is a mechanism of adaptation that does not involve mutations. Epigenetics is the study of changes in the phenotype that cannot be attributed to changes in the genotype. Typically, studies revolve around two features of the chromosomes: cytosine methylation and histone modifications. The former can influence how proteins interact with DNA, and the latter can influence protein access to DNA. Both can affect each other in self-reinforcing loops. They can affect gene expression, and DNA methylation can be directed by small RNA (sRNA), which can also influence gene expression through other pathways. To study these processes and their role in abiotic stress response, we aimed to analyze sRNA, RNA, and DNA from Arabidopsis thaliana plants under stress. The stresses applied were sublethal doses of the herbicides, glyphosate and trifloxysulfuron, as well as mechanical clipping and shade to represent other weed management stressors. The focus of the project was to analyze these responses individually and together to find epigenetic responses to stresses routinely encountered by weeds. We tested RNA for gene expression changes under our stress conditions and identified many, including some pertaining to DNA methylation regulation. The herbicide treatments were associated with upregulated defense genes and downregulated growth genes. Shade treated plants had many downregulated defense and other stress response genes. We also detected differential methylation and sRNA responses when compared to the control plants. Changes to methylation and sRNA only accounted for about 20% of the variation in gene expression. While attempting to link the epigenetic process of methylation to gene expression, we connected all the data sets and developed computer programs to try to make correlations. While these methods worked on a simulated dataset, we did not detect broad patterns of changes to epigenetic pathways that correlated strongly with gene expression in our experiment's data. There are many factors that can influence gene expression that could create noise that would hinder the algorithms' abilities to detect differentially expressed genes. This does not, however, rule out the possibility of epigenetic influence on gene expression in local contexts. Through scoring the traits of individual genes, we found several that interest us for future studies.

L’objectif de cette thèse est de déterminer l’étendue de la variabilité épigénétique, plus particulièrement du polymorphisme de méthylation de l’ADN, non liée à la variabilité génétique dans les populations asexuées en milieu naturel. Cette évaluation nous a permis de mieux cerner l’importance que peuvent avoir les processus épigénétiques en écologie et en évolution. Le modèle biologique utilisé est l’hybride clonal du complexe gynogénétique Chrosomus eos-neogaeus. Malgré une homogénéité génétique, une importante variabilité phénotypique est observée entre les hybrides d’une même lignée clonale mais retrouvés dans des environnements différents. L’influence des processus épigénétiques apporte une explication sur ce paradoxe. L’épigénétique se définit comme une modification de l’expression des gènes sans changement de la séquence d’ADN. La diversité des phénotypes peut entre autre s’expliquer par des patrons de méthylation différentiels des gènes et/ou des allèles des gènes entre les hybrides génétiquement identiques. La diversité des lignées épiclonales peut quant à elle s’expliquer par la colonisation de plusieurs lignées épiclonales, s’établir en réponse à l’environnement ou de façon aléatoire. Plusieurs méthodes seront utilisées afin de survoler le génome des hybrides clonaux pour mettre en évidence le polymorphisme de méthylation de l’ADN à l’échelle de l’individu et entre les individus de différentes populations. / The aim of the thesis is to determine the extent of epigenetic variation, more specifically DNA methylation polymorphism, not linked to genetic variation in natural populations of an asexual vertebrate. This evaluation enables to better understand the importance that plays epigenetics processes in ecology and evolution. The biological model used is the clonal hybrid of the gynogenetic Chrosomus eos-neogaeus complex. Even in absence of genetic difference, an important phenotypic variability is observed among hybrids of the same clonal lineage living in different environments. Epigenetics, a modification of genes expression without a change at the DNA sequence, provides an explanation to this paradox. The diversity of phenotypes may be explained by differential methylation patterns of genes and/or alleles among genetically identical hybrids. The diversity of epiclonal lineages may be explained by the colonisation of many epiclonal lineages, established in response to the environment or stochastically. Many methods were used for screening the genome of clonal hybrids in order to highlight DNA methylation polymophism at the scale of an individual and among individuals of different populations.

L’objectif de cette thèse est de déterminer l’étendue de la variabilité épigénétique, plus particulièrement du polymorphisme de méthylation de l’ADN, non liée à la variabilité génétique dans les populations asexuées en milieu naturel. Cette évaluation nous a permis de mieux cerner l’importance que peuvent avoir les processus épigénétiques en écologie et en évolution. Le modèle biologique utilisé est l’hybride clonal du complexe gynogénétique Chrosomus eos-neogaeus. Malgré une homogénéité génétique, une importante variabilité phénotypique est observée entre les hybrides d’une même lignée clonale mais retrouvés dans des environnements différents. L’influence des processus épigénétiques apporte une explication sur ce paradoxe. L’épigénétique se définit comme une modification de l’expression des gènes sans changement de la séquence d’ADN. La diversité des phénotypes peut entre autre s’expliquer par des patrons de méthylation différentiels des gènes et/ou des allèles des gènes entre les hybrides génétiquement identiques. La diversité des lignées épiclonales peut quant à elle s’expliquer par la colonisation de plusieurs lignées épiclonales, s’établir en réponse à l’environnement ou de façon aléatoire. Plusieurs méthodes seront utilisées afin de survoler le génome des hybrides clonaux pour mettre en évidence le polymorphisme de méthylation de l’ADN à l’échelle de l’individu et entre les individus de différentes populations. / The aim of the thesis is to determine the extent of epigenetic variation, more specifically DNA methylation polymorphism, not linked to genetic variation in natural populations of an asexual vertebrate. This evaluation enables to better understand the importance that plays epigenetics processes in ecology and evolution. The biological model used is the clonal hybrid of the gynogenetic Chrosomus eos-neogaeus complex. Even in absence of genetic difference, an important phenotypic variability is observed among hybrids of the same clonal lineage living in different environments. Epigenetics, a modification of genes expression without a change at the DNA sequence, provides an explanation to this paradox. The diversity of phenotypes may be explained by differential methylation patterns of genes and/or alleles among genetically identical hybrids. The diversity of epiclonal lineages may be explained by the colonisation of many epiclonal lineages, established in response to the environment or stochastically. Many methods were used for screening the genome of clonal hybrids in order to highlight DNA methylation polymophism at the scale of an individual and among individuals of different populations.

Os genes de receptores olfatórios (OR) pertencem a uma família de proteínas de membrana formada por cerca de 1000 genes no genoma de camundongo. Os genes OR são expressos de forma monogênica e monoalélica nos neurônios olfatórios (OSNs). No entanto, ainda não está claro o mecanismo que permite essa forma de expressão peculiar, sobretudo, qual o papel da metilação de DNA nesse processo. Nosso estudo determinou o padrão de metilação de DNA da região promotora e codificadora do gene Olfr17. Em células de epitélio olfatório (MOE) de camundongos adultos, observamos na região codificadora (CDS) do gene uma frequência de metilação em dinucleotídeos CpG 58%, enquanto que na sua região promotora ela foi bem mais baixa. Os níveis de metilação do Olfr17 em MOE de embrião (E15.5) e fígado foram similares aos observados em MOE de animais adultos. Em seguida, analisamos se a metilação de DNA pode regular a expressão gênica do Olfr17. Utilizando animais transgênicos onde os neurônios olfatórios que expressam Olfr17 também expressam GFP, pudemos selecionar neurônios olfatórios GFP+ e analisar a metilação do gene Olfr17, que está ativo nestas células. Verificamos que o padrão geral de metilação do Olfr17, tanto na região CDS como na região promotora, não se altera quando este gene está ativo. Este resultado indica que alterações na metilação do gene Olfr17 não são necessárias para que este receptor seja expresso. Finalmente, verificamos que a região promotora do gene Olfr17, de duas linhagens de camundongos diferentes, a C57BL/6 e a 129, possuem dois polimorfismos de base única (SNPs) que alteram o conteúdo CpG. Devido a estes SNPs, a linhagem 129 apresenta dois sítios CpG adicionais, inexistentes na linhagem C57BL/6. Nossas análises mostraram que estes CpGs são frequentemente metilados, o que torna o promotor do Olfr17 de 129 significativamente mais metilado que o promotor de C57BL/6. Em seguida, nós analisamos o nível de expressão no MOE dos dois alelos de Olfr17, o 129 e o C57BL/6, utilizando ensaios de RT-qPCR. Estes experimentos demonstraram que o nível de expressão do alelo 129, que possui 3 CpGs metiladas em seu promotor, é menor que o do alelo C57BL/6, que apresenta apenas uma CpG que é pouco metilada em seu promotor. Nossos resultados sugerem que as alterações na região promotora influenciam a probabilidade com que o gene OR é escolhido para ser expresso no MOE. / Olfactory receptor (OR) genes belong to a large family of membrane proteins composed of 1000 genes in the mouse genome. The OR genes are expressed in the olfactory sensory neurons (OSNs) in a monogenic and monoallelic fashion. However, the mechanisms that govern OR gene expression are unclear. Here we asked whether DNA methylation plays a role in the regulation of OR gene expression. We first determined the DNA methylation pattern in the coding (CDS) and promoter regions of the odorant receptor gene Olfr17. In olfactory epithelium (MOE) cells, the CpG methylation level in the CDS is 58% but is much lower in the promoter region of the gene. In embryonic MOE (E15.5) and liver, the levels of Olfr17 DNA methylation are similar to the ones shown in adult MOE. We next analyzed whether DNA methylation is involved in Olfr17 regulation. We isolated GFP+ neurons from transgenic mice that coexpress GFP with Olfr17, and analyzed the DNA methylation pattern of the Olfr17, which is active in these cells. We found that the general methylation pattern, both, in the coding and promoter regions is not altered in the active gene. These results indicate that changes in DNA methylation are not required for the activation of Olfr17. Finally, we found that the Olfr17 promoter region from two different mouse strains, C57BL/6 and 129, has two single-nucleotide polymorphisms (SNPs) that alter the CpG content. The SNPs lead to the existence of two additional CpGs in the 129 allele, which are absent in the C57BL/6 allele. These CpGs are frequently methylated, making the 129 Olfr17 promoter significantly more methylated than the Olfr17 promoter from C57BL/6. We next performed RT-qPCR experiments to analyze the expression levels of the 129 and C57BL/6 Olfr17 alleles in the MOE. These experiments showed that the expression level of the 129 Olfr17 allele, which contains three methylated CpGs in its promoter region, is lower than the one from C57BL/6, which contains only one, undermethylated CpG, in its promoter. Our results suggest that these promoter modifications regulate the probability of the OR gene choice.

En mamíferos, así como en plantas, mutaciones en AND helicasas/ATPasas del la família SNF2, no solo afectan a la estructura de la cromatina, sino que también afectan al patrón global de la metilación del ADN. Sugiriendo una relación funcional entre la estructura de la cromatina y la epigenética. El complejo NuRD, el cual posee una ATPasa de la familía SNF2, está relacionado con la represión de la transcripción y en el remodelamiento de la cromatina. Nuestro laboratorio demostró que la proteína leucémica PML-RARα reprime la transcripción de sus genes diana por el reclutamiento de DNMTs y el complejo PRC2. En esta tesis, demostramos una relación directa del complejo NuRD en la represión génica y en los cambios epigenéticos en la leucemia promielocítica aguda (APL). Mostramos que PML-RARα se une y recluta NuRD a sus genes diana, incluyendo el gen supresor de tumores RAR2, facilitando que el complejo de Polycomb se reclute y metile la lisina 27 de la histona H3. Tratamiento con Acido Retinóico (RA), el qual se utiliza en pacientes, reduce la ocupación de NuRD en células leucémicas. Eliminando NuRD no solo provoca que las histonas no se deacetilen y que la cromatina no se compacte, sino que también provoca que tanto la metilación del ADN y de las histonas no se produzca, así como la represión génica del gen RAR2, favoreciendo la diferenciación celular. Nuestros resultados caracterizan un nuevo papel del complejo NuRD en el establecimiento de los patrones epigenéticos en APL, demostrando una relación esencial entre la estructura de la cromatina y epigenética durante el desarrollo de la leucemia, pudiéndose aplicar a la terapia de esta enfermedad. / In mammals, as in plants, mutations in SNF2-like DNA helicases/ATPases were shown to affect not only chromatin structure but also global methylation patterns, suggesting a potential functional link between chromatin structure and epigentic marks. The SNF2-like containing NuRD complex is involved in gene transcriptional repression and chromatin remodeling. We have previously shown that the leukemogenic protein PMLRARα represses target genes through recruitment of DNMTs and Polycomb complex. In this thesis, we demonstrate a direct role of the NuRD complex in aberrant gene repression and transmission of epigenetic repressive marks in acute promyelocytic leucemia (APL). We show that PML-RARα binds and recruits NuRD to target genes, including to the tumor-suppressor gene RAR2. In turn, the NuRD complex facilitates Polycomb binding and histone methylation at lysine 27. Retinoic acid treatment reduced the promoter occupancy of the NuRD complex. Knock-down of the NuRD complex in leukemic cells not only prevented histone deacetylation and chromatin compaction, but also impaired DNA and histone methylation as well as stable silencing, thus favoring cellular differentiation. These results unveil an important role for NuRD in the establishment of altered epigenetic marks in APL, demonstrating an essential link between chromatin structure and epigenetics in leukemogenesis that could be exploited for therapeutic intervention.

Os genes de receptores olfatórios (OR) pertencem a uma família de proteínas de membrana formada por cerca de 1000 genes no genoma de camundongo. Os genes OR são expressos de forma monogênica e monoalélica nos neurônios olfatórios (OSNs). No entanto, ainda não está claro o mecanismo que permite essa forma de expressão peculiar, sobretudo, qual o papel da metilação de DNA nesse processo. Nosso estudo determinou o padrão de metilação de DNA da região promotora e codificadora do gene Olfr17. Em células de epitélio olfatório (MOE) de camundongos adultos, observamos na região codificadora (CDS) do gene uma frequência de metilação em dinucleotídeos CpG 58%, enquanto que na sua região promotora ela foi bem mais baixa. Os níveis de metilação do Olfr17 em MOE de embrião (E15.5) e fígado foram similares aos observados em MOE de animais adultos. Em seguida, analisamos se a metilação de DNA pode regular a expressão gênica do Olfr17. Utilizando animais transgênicos onde os neurônios olfatórios que expressam Olfr17 também expressam GFP, pudemos selecionar neurônios olfatórios GFP+ e analisar a metilação do gene Olfr17, que está ativo nestas células. Verificamos que o padrão geral de metilação do Olfr17, tanto na região CDS como na região promotora, não se altera quando este gene está ativo. Este resultado indica que alterações na metilação do gene Olfr17 não são necessárias para que este receptor seja expresso. Finalmente, verificamos que a região promotora do gene Olfr17, de duas linhagens de camundongos diferentes, a C57BL/6 e a 129, possuem dois polimorfismos de base única (SNPs) que alteram o conteúdo CpG. Devido a estes SNPs, a linhagem 129 apresenta dois sítios CpG adicionais, inexistentes na linhagem C57BL/6. Nossas análises mostraram que estes CpGs são frequentemente metilados, o que torna o promotor do Olfr17 de 129 significativamente mais metilado que o promotor de C57BL/6. Em seguida, nós analisamos o nível de expressão no MOE dos dois alelos de Olfr17, o 129 e o C57BL/6, utilizando ensaios de RT-qPCR. Estes experimentos demonstraram que o nível de expressão do alelo 129, que possui 3 CpGs metiladas em seu promotor, é menor que o do alelo C57BL/6, que apresenta apenas uma CpG que é pouco metilada em seu promotor. Nossos resultados sugerem que as alterações na região promotora influenciam a probabilidade com que o gene OR é escolhido para ser expresso no MOE. / Olfactory receptor (OR) genes belong to a large family of membrane proteins composed of 1000 genes in the mouse genome. The OR genes are expressed in the olfactory sensory neurons (OSNs) in a monogenic and monoallelic fashion. However, the mechanisms that govern OR gene expression are unclear. Here we asked whether DNA methylation plays a role in the regulation of OR gene expression. We first determined the DNA methylation pattern in the coding (CDS) and promoter regions of the odorant receptor gene Olfr17. In olfactory epithelium (MOE) cells, the CpG methylation level in the CDS is 58% but is much lower in the promoter region of the gene. In embryonic MOE (E15.5) and liver, the levels of Olfr17 DNA methylation are similar to the ones shown in adult MOE. We next analyzed whether DNA methylation is involved in Olfr17 regulation. We isolated GFP+ neurons from transgenic mice that coexpress GFP with Olfr17, and analyzed the DNA methylation pattern of the Olfr17, which is active in these cells. We found that the general methylation pattern, both, in the coding and promoter regions is not altered in the active gene. These results indicate that changes in DNA methylation are not required for the activation of Olfr17. Finally, we found that the Olfr17 promoter region from two different mouse strains, C57BL/6 and 129, has two single-nucleotide polymorphisms (SNPs) that alter the CpG content. The SNPs lead to the existence of two additional CpGs in the 129 allele, which are absent in the C57BL/6 allele. These CpGs are frequently methylated, making the 129 Olfr17 promoter significantly more methylated than the Olfr17 promoter from C57BL/6. We next performed RT-qPCR experiments to analyze the expression levels of the 129 and C57BL/6 Olfr17 alleles in the MOE. These experiments showed that the expression level of the 129 Olfr17 allele, which contains three methylated CpGs in its promoter region, is lower than the one from C57BL/6, which contains only one, undermethylated CpG, in its promoter. Our results suggest that these promoter modifications regulate the probability of the OR gene choice.