Project description:Monodelphis domestica develops ex utero. Here, we have investigated the changes in the transcriptomics of adipose tissue during juvenile development to get further insights into the reprograming in marsupial mammals.
Project description:Marsupials have been a powerful comparative model to understand mammalian biology. However, because of the unique characteristics of their embryology, marsupial pluripotency architecture remains to be fully understood, and nobody has succeeded in developing embryonic stem cells (ESCs) from any marsupial species. We have developed an integration-free induced pluripotent stem cell (iPSC) reprogramming method and established validated iPSC lines from two fully inbred strains of the gray short-tailed opossum (Monodelphis domestica). A comprehensive characterization of the M. domestica skin fibroblasts and their reprogrammed iPSCs was performed by genome-wide mRNA sequencing. The established monoiPSCs showed a significant (6,181 DE genes) but highly uniform (between clone r2 at 95% CI = 0.973 ± 0.007) resetting of the cellular transcriptome during reprogramming and were highly similar to eutherian ESCs and iPSCs in their overall transcriptomic and functional profiles. However, monoiPSCs showed unique regulatory architecture of the core pluripotency transcription factors and were more like epiblasts. Our results suggest POU5F1 and the splice variant specific expression of POU5F3 synergistically regulate the opossum pluripotency gene network. It is plausible that POU5F1, POU5F3 splice variant XM_016427856.1, and SOX2 form a self-regulatory network. NANOG expression, however, was specific to monoiPSCs and epiblasts, and displayed a distinct expression profile in embryonic cells. Furthermore, POU5F1 was highly expressed in trophectoderm cells, whereas all other pluripotency transcription factors were significantly downregulated, suggesting that the regulatory architecture of core pluripotency genes of marsupials may be distinct from that of eutherians.
Project description:Multiple mammalian lineages independently evolved a definitive mammalian middle ear (DMME) through breakdown of Meckel’s cartilage (MC). However, the cellular and molecular drivers of this evolutionary transition remain unknown for most mammal groups. Here, we identify such drivers in the living marsupial opossum Monodelphis domestica, whose MC transformation during development anatomically mirrors the evolutionary transformation observed in fossils. Specifically, we link increases in cellular apoptosis and TGF-BR2 signalling to MC breakdown in opossums. We demonstrate that a simple change in TGF-b signalling is sufficient to inhibit MC breakdown during opossum development, indicating that changes in TGF-b signalling might be key during mammalian evolution. Furthermore, the apoptosis that we observe during opossum MC breakdown does not seemingly occur in mouse, consistent with homoplastic DMME evolution in the marsupial and placental lineages.
Project description:Evidence from a few genes of diverse species suggests that marsupial X-chromosome inactivation (XCI) is characterized by exclusive, but leaky, inactivation of the paternally derived X chromosome. To comprehensively study the mechanism of marsupial XCI, we profiled parent-of-origin-specific-allele expression, DNA methylation, and histone modifications in opossum fetal brain and extra-embryonic membranes. The majority (152/176) of X-linked genes exhibited paternally imprinted expression with nearly 100% maternal allele expression, whereas 24 loci (14%) escaped inactivation showing varying levels of biallelic expression. In addition to regulation by the non-coding RSX transcript, strong depletion of H3K27me3 at escaper gene loci indicates that histone states also influence opossum XCI. Notably, the opossum does not show an association between X-linked gene expression and promoter DNA methylation. Our study provides the first comprehensive catalogue of parent-of-origin expression status for X-linked genes in a marsupial and sheds light on the regulation and evolution of imprinted XCI in mammals. Profiling of four histone modifications in embryonic day 13 opossum (Monodelphis domestica) fetal brain by Illumina ChIP-seq