Phd Studentship: The Biology of Suspended Animation

Diapause is a natural process by which an organism enters a state of suspended animation in response to environmental challenges. Diapause is unique from other dormancies (e.g. quiescence) as the stage, entry and length of developmental arrest is endogenously programmed in advance of onset, and may be either facultative or obligatory. The environmental genomics model organism Daphnia produces diapausing embryos as part of its reproductive cycle. When buried in the lake sediments, these embryos produce a living archive of past populations that can be sampled and resuscitated in the laboratory after prolonged periods of time. Investigators at the University of Birmingham have hatched these dormant embryos to resume development, producing healthy reproductive adults, even after 700 years of sustained developmental arrest. From these hatchlings, populations of Daphnia that are native to Europe and to North America are indefinitely maintained in the laboratory for evolutionary studies through 10,000 generations. Our work at co-advising a student (Ms Rosemary Barnett who is now submitting her thesis) discovered that the development of embryos destined to diapause is delayed compared to non-diapausing embryos until arrested, after roughly eleven rounds of cellular divisions (over 3500 cells) whereupon mitotic activity is absent, cytoskeletal components are depleted and cells are condensed for these exceptionally long periods of metabolic inertness. Her analysis by statistical machine learning of a multiomics datasets comparing the developmental programmes of both types of embryos, revealed both recognizable and newly discovered regulatory pathways, having significant implications on our understanding of the plasticity of developmental programmes towards two extreme life-history stages, and how life can be suspended for centuries of environmental hardship.
This next CENTA PhD Project Proposal follows upon these initial molecular biological findings from observing the entry into diapause, to now discover the process by which a diapausing embryo “senses” environmental cues to subsequently resume development. The student will investigate the degree to which diapausing embryos are reactive to environmental signals and perturbations as a function of time at dormancy, and whether the breaking of diapause consists of a reversal of molecular and cellular events that had earlier prepared the embryos for suspended animation.
This project is closely associated with other research at the University of Birmingham and beyond that focuses on the study of diapausing Daphnia populations buried in lake sediments so to uniquely witness the molecular mechanisms of adaptive evolution in natural populations over decades and centuries against the documented environmental changes that have occurred from local to regional scales (called resurrection biology). As such, partners and collaborators include the Natural History Museum (ancient DNA research), the UK MetOffice (climate change), Natural England and the Environment Agency (biodiversity in the face of pollutants).
Any questions about the project can be directed to:Professor John Colbourne

Funding Notes

CENTA studentships are for 3.5 years and are funded by NERC. In addition to the full payment of their tuition fees, successful candidates will receive the following financial support:

Annual stipend, set at £14,777 for 2018/19
Research training support grant (RTSG) of £8,000

 

References

Chen, L., R.E. Barnett, M. Horstmann, V. Bamberger, L. Heberle, N. Krebs, J.K. Colbourne, R. Gómez, and L.C. Weiss. Mitotic activity patterns and cytoskeletal changes throughout the progression of diapause developmental program in Daphnia. Submitted.

Nogués-Bravo D. Rodríguez-Sánchez F., L. Orsini, E. de Boer, R. Jansson, H. Morlon, D. Fordham and S. Jackson. 2018. Cracking the code of past biodiversity responses to climate change. Trends in Ecology and Evolution 33: 765-776.

Cuenca Cambronero M. and L. Orsini. 2018. Resurrection of dormant Daphnia magna: Protocol and applications. Journal of Visualized Experiments 131: e56637.
Kvist, J., C.G. Athanàsio, O.S. Solari, J.B. Brown, J.K. Colbourne, M.E. Pfrender and L. Mirbahai. 2018. Pattern of DNA methylation in Daphnia: Evolutionary perspective. Genome Biology and Evolution, evy155, https://doi.org/10.1093/gbe/evy155.

Frisch, D., P.K. Morton, P. Roy Chowdhury, B.W. Culver, J.K. Colbourne, L.J. Weider and P.D. Jeyasingh. 2014. A millennial-scale chronicle of evolutionary responses to cultural eutrophication in Daphnia. Ecology Letters 17: 360-368.

Colbourne, J.K., M.E. Pfrender, D. Gilbert, W.K. Thomas, et al. 2011. The ecoresponsive genome of Daphnia pulex. Science 331: 555-561.