G-enomic imprinting is an epigenetic mechanism that produces functional differences between the paternal and mammal genomes and plays an essential role in mammalian development and growth. There are a number of genes ...G-enomic imprinting is an epigenetic mechanism that produces functional differences between the paternal and mammal genomes and plays an essential role in mammalian development and growth. There are a number of genes in our genomes that are subject to genomic imprinting where one parent＇s copy of the gene is expressed while the other is silent. Silencing of one allele predetermines that any function ascribed to that gene are now dependant on the single active copy. Possession of only a single active allele can lead to deleterious health consequences in humans. If imprinted genes are crucial in mammalian development, one would also expect mutations in these genes to cause diseases. Since imprinting is an epigenetic mechanism, mistakes in maintaining epigenetic mark also cause imprinting disorders. Here we in this review focus on the current understanding of this unique genetic mechanism more than two decades after the first description of the imprinting phenomenon was given by McGrath and Solter. Although the possible molecular mechanisms by which imprinting is imposed and maintained are being identified, we have a long way to go in understanding the molecular mechanisms that regulate the expression of these oddly behaving genes, the function of imprinting and the evolution. Post genomic technologies might ultimately lead to a better understanding of the ＇imprinting effects＇.展开更多
Epigenetic processes are important mechanisms for phenotypic changes that occur in response to the environment. As such, it is expected that the alteration of cytoplasmic composition （the immediate environment of nuc...Epigenetic processes are important mechanisms for phenotypic changes that occur in response to the environment. As such, it is expected that the alteration of cytoplasmic composition （the immediate environment of nuclei） results in the modifica- tion of the methylome and the expression of the nuclear genome. Cytoplasmic hybrids （or cybrids） are an ideal model to study the influence of mitochondria on gene expression. In this study, we take advantage of the natural of two biotypes that have a similar nuclear genome type Chrosomus eos, but harbor mitochondria from different species （C. eos in wild type or C. neogaeus in cybrids） to assess the effects of mitochondria on DNA methylation profiles and protein expression of the nuclear ge- nome. Comparison between these biotypes is particularly relevant given their recent divergence and their low level of genetic dif- ferentiation. Variations of DNA methylation assessed on tissues from different embryonic origins revealed the distinct profiles of cybrid and wild type populations. Differences are more pronounced between wild type and cybrids than between populations of a given biotype. The proteome is also more different between biotypes than within a given biotype. These results indicate a strong influence of mitochondria on the nuclear genome, which remains detectable in different genetic and environmental contexts. These changes in the methylome and proteome of cybrids are expected to reflect the adjustments imposed by the coexistence of nuclear and mitochondrial genomes from different species [Current Zoology 58 （1）： 138-145, 2012].展开更多
文摘G-enomic imprinting is an epigenetic mechanism that produces functional differences between the paternal and mammal genomes and plays an essential role in mammalian development and growth. There are a number of genes in our genomes that are subject to genomic imprinting where one parent＇s copy of the gene is expressed while the other is silent. Silencing of one allele predetermines that any function ascribed to that gene are now dependant on the single active copy. Possession of only a single active allele can lead to deleterious health consequences in humans. If imprinted genes are crucial in mammalian development, one would also expect mutations in these genes to cause diseases. Since imprinting is an epigenetic mechanism, mistakes in maintaining epigenetic mark also cause imprinting disorders. Here we in this review focus on the current understanding of this unique genetic mechanism more than two decades after the first description of the imprinting phenomenon was given by McGrath and Solter. Although the possible molecular mechanisms by which imprinting is imposed and maintained are being identified, we have a long way to go in understanding the molecular mechanisms that regulate the expression of these oddly behaving genes, the function of imprinting and the evolution. Post genomic technologies might ultimately lead to a better understanding of the ＇imprinting effects＇.
文摘Epigenetic processes are important mechanisms for phenotypic changes that occur in response to the environment. As such, it is expected that the alteration of cytoplasmic composition （the immediate environment of nuclei） results in the modifica- tion of the methylome and the expression of the nuclear genome. Cytoplasmic hybrids （or cybrids） are an ideal model to study the influence of mitochondria on gene expression. In this study, we take advantage of the natural of two biotypes that have a similar nuclear genome type Chrosomus eos, but harbor mitochondria from different species （C. eos in wild type or C. neogaeus in cybrids） to assess the effects of mitochondria on DNA methylation profiles and protein expression of the nuclear ge- nome. Comparison between these biotypes is particularly relevant given their recent divergence and their low level of genetic dif- ferentiation. Variations of DNA methylation assessed on tissues from different embryonic origins revealed the distinct profiles of cybrid and wild type populations. Differences are more pronounced between wild type and cybrids than between populations of a given biotype. The proteome is also more different between biotypes than within a given biotype. These results indicate a strong influence of mitochondria on the nuclear genome, which remains detectable in different genetic and environmental contexts. These changes in the methylome and proteome of cybrids are expected to reflect the adjustments imposed by the coexistence of nuclear and mitochondrial genomes from different species [Current Zoology 58 （1）： 138-145, 2012].
