Transdifferentiation in Turritopsis dohrnii (Immortal Jellyfish): Model System for Regeneration, Cellular Plasticity and Aging
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Turritopsis dohrnii (Cnidaria, Hydrozoa) undergoes life cycle reversal to avoid death caused by physical damage, adverse environmental conditions, or aging. This unique ability has granted the species the name, the “Immortal Jellyfish”. T. dohrnii exhibits an additional developmental stage to the typical hydrozoan life cycle which provides a new paradigm to further understand regeneration, cellular plasticity and aging. Weakened jellyfish will undergo a whole-body transformation into a cluster of uncharacterized tissue (cyst stage) and then metamorphoses back into an earlier life cycle stage, the polyp. The underlying cellular processes that permit its reverse development is called transdifferentiation, a mechanism in which a fully mature and differentiated cell can switch into a new cell type. It was hypothesized that the unique characteristics of the cyst would be mirrored by differential gene expression patterns when compared to the jellyfish and polyp stages. Specifically, it was predicted that the gene categories exhibiting significant differential expression may play a large role in the reverse development and transdifferentiation in T. dohrnii. The polyp, jellyfish and cyst stage of T. dohrnii were sequenced through RNAsequencing, and the transcriptomes were assembled de novo, and then annotated to create the gene expression profile of each stage. Comparative functional gene enrichment analyses with the cyst as the central stage of comparison reported significant GO categories that were over-expressed, such as telomere maintenance and DNA repair, in the cyst as compared to other stages. The enrichment analyses also reported significantly under-expressed categories, such as mitotic cell division and cellular differentiation, in the cyst as compared to the other stages. Additionally, candidate genes, such as the Yamanaka (Oct4, Sox2, Klf4, c-Myc) and Thompson Factors (Lin28, Nanog) that exhibit potential association with the transdifferentiation processes were found among the three stages for downstream differential gene expression analyses. Ultimately, our work produced a foundation to develop an alternative model system to further investigate and comprehend regeneration, cellular plasticity and aging in metazoans.
Matsumoto, Yui (2017). Transdifferentiation in Turritopsis dohrnii (Immortal Jellyfish): Model System for Regeneration, Cellular Plasticity and Aging. Master's thesis, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /173118.