Imprinting Part 1 Flashcards
what is a reciprocal cross in terms of using mice to look at imprinted genes?
it involves crossing mice from two different strains, where you know the strain of the mother and father. This allows you to see whether the paternal or maternal allele is being expressed in the offspring and thus determine which copy is imprinted.
describe how SNPs can be used to look at the presence of imprints?
This was accomplished by directly counting the number reference/alternative allele containing reads at polymorphic SNP positions in the parental genome.
what is advantageous about the diploid state?
confers on organisms increased protection against the effects of ay exposure to deleterious mutations occurring on one allele.
what is the kinship theory of why imprinting exists?
predicts that paternally expressed genes are driven to promote fatal growth by extracting maximal resources from the mother, especially in polygamous populations. In contrast, the maternal genome discourages offspring growth by limiting its share of her resources, and ensures her survival and equal allocation of nutrients among her offspring. consistently, imprinting is observed to occur predominately in genes influencing fatal growth.
what does DMR mean?
differentially methylated region
how are imprinted genes normally organised?
in clusters, many of which are under control of the cis-acting loci called imprinting control regions.
why is a CpG associated with imprinting?
because sites of enriched CpGs are totally subject to allelic DNA methylation, and DNA methylation is generally associated with repressed transcription
In mammals, when are the two major genome-wide epigenetic reprogramming events?
gemetogenesis and early embryogenesis.
when is the hypomethylation event in which the imprints must be protected?
pre-implantation
when are the sex specific imprints established?
in the germ cells during their development
what are the three functional DNA methyltransferases that have been described in mammals?
DNMT1, DNMT2, DNMT3b.
how is methylation normally found in animals?
addition of a methyl group to the caron-5 position of cytosine residues of the CpG
what does the treatment of DNA with bisulfites cause?
converts cytosine residues to uracil, but leaves methyl-cytosine residues unaffected.
very briefly, what was the general experiment which first highlighted ZFP’s role in imprinting?
they performed high throughput and multi-locus analyses of inbred and hybrid mouse ESC lines carrying different gene knockouts. By using an allele specific RNA seq-approach, they demonstrated that ZFP57 loss results in derepression of the imprint of multiple genes in the imprinted clusters. This suggested that ZFP57 was pivotal to maintain the allele specific epigenetic modifications of ICRs that in turn are needed to maintain imprint expression.
what is the co-repressor of ZFP57?
KRAB-A-interacting protein (KAP1)
