Related Experiment Video
Updated: Jun 30, 2026
07:39
Mouse In Vivo Placental Targeted CRISPR Manipulation
Published on: April 14, 2023
Genomic imprinting in marsupial placentation
Marilyn B Renfree1, Eleanor I Ager, Geoff Shaw
1Department of Zoology, ARC Centre of Excellence for Kangaroo Genomics, The University of Melbourne, Melbourne, Victoria 3010, Australia. m.renfree@unimelb.edu.au
Reproduction (Cambridge, England)
|September 23, 2008
Summary
Genomic imprinting, an epigenetic process, shows conserved gene expression in marsupial placentas. Unlike eutherians, marsupials use histone modification, not DNA methylation, for some imprinted genes, with retrotransposons driving new imprints.
Area of Science:
- Epigenetics
- Developmental Biology
- Evolutionary Biology
Background:
- Genomic imprinting regulates mammalian growth and development.
- The parental conflict hypothesis explains imprinting evolution.
- Marsupials offer insights into imprinting's evolution due to viviparity and short gestation.
Purpose of the Study:
- Investigate the evolution and acquisition of genomic imprinting.
- Examine imprinting mechanisms in marsupials.
- Determine the correlation between imprinting, viviparity, and placentation.
Main Methods:
- Comparative analysis of imprinted gene orthologues in marsupials and eutherians.
- Examination of differentially methylated regions (DMRs) in marsupial placentas.
- Investigation of histone modification as a silencing mechanism.
Main Results:
- Conserved expression of eutherian imprinted genes in marsupial placentas.
- Absence of DMRs in marsupial IGF2R, INS, and MEST orthologues; histone modification identified as a silencing mechanism.
- Presence of DMRs in marsupial H19, IGF2, and PEG10 genes; PEG10 evolution linked to retrotransposon insertion.
Conclusions:
- Genomic imprinting mechanisms differ between marsupials and eutherians.
- Retrotransposon insertion can drive the evolution of imprinted regions and DMRs.
- Imprinting is correlated with viviparity but not necessarily with complex placentation.
Related Concept Videos
02:30Genomic Imprinting and Inheritance
Diploid organisms inherit genetic material through chromosomes from both parents. Copies of the same gene are known as alleles. In most cases, both alleles are simultaneously expressed and allow various cellular processes to function optimally. If one of the alleles is missing or mutated, the expression of the other allele can compensate; however, this is not true for all genes.
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
The expression of some genes depends on which parent passed the gene to the offspring, through a phenomenon known as...
01:22Imprinting
Behavioral imprinting is observed in some newborn animals and occurs when they develop strong and specific attachments to another animal (usually a parent) following brief, early-life exposures. Offspring imprint onto parents within a brief period after birth or hatching; this time window is called the critical period. Once imprinting occurs, the bond established between the parents and their offspring is usually long-lasting.
02:59Animal Mitochondrial Genetics
Among all the organelles in an animal cell, only mitochondria have their own independent genomes. Animal mitochondrial DNA is a double-stranded, closed-circular molecule with around 20,000 base pairs. Mitochondrial DNA is unique in that one of its two strands, the heavy, or H, -strand is guanine rich, whereas the complementary strand is cytosine rich and called the light, or L, -strand. Compared to nuclear DNA, mitochondrial DNA has a very low percentage of non-coding regions and is marked by...