YAG PhD-projects 2019

Aude Giraud

Inheritance of acquired characters: Past and present controversy - and the way forward

Supervisors: Dr. Han Thomas Adriaenssen (Philosophy - History of Philosophy) and Dr. Martine Maan (Science and Engineering - GELIFES)

The French Biologist Jean-Baptiste Lamarck (1744-1829) is best remembered nowadays for his claim that physical characteristics an animal acquires during his life are passed on to its offspring, and that the inheritance of acquired characteristics is a main force driving the transformation of species. Lamarck's ideas have often been met with scepticism, but recent developments in molecular genetics, such as epigenetics, have inspired a re-evaluation of his legacy.

In this project, we explore what modern biology can, or cannot, learn from Lamarck, and ask how modern-day Lamarckism compares to the original ideas proposed in the eighteenth and nineteenth centuries by Lamarck. So far, we have been looking at (1) the historical development of the notion of epigenesis, (2) the contemporary debates on the concept of epigenetics, and (3) Lamarck's account in the 1809 Philosophie Zoologique of the transformation of species over time and the inheritance of environmentally induced changes. A manuscript provideing a systematic comparison of Lamarckian inheritance of acquired traits on the one hand and inheritance of epigenetic states on the other is currently in preparation. An experiment on plasticity in drosophilia, testing Lamarckian hypotheses regarding organisims' ability to adapt to changing environmental conditions, is ongoing.

Joelle Jagersma

The social, cognitive and neurobiological impact of hearing loss in youth

Supervisors: Dr. Jocelien Olivier (GELIFES - Faculty of Science and Engineering) and Dr. Sonja Pyott (Otorhinolaryngology - Faculty of Medical Sciences)

Extensive research indicates that children with hearing loss show intellectual and social interaction disabbilities. However, the underlying neurobiological mechanisms are largely unknown. For these reasons this project, conducted by Joëlle Jagersma under the supervision of YAG members Jocelien Olivier and Sonja Pyott, aims to develop animal models to test the effect of hearing loss on social and cognitive behaviors and its underlying neurobiology.

We have established a rat model with early, mild hearing loss. Behaviorally, mild hearing loss induced by noise exposure in young rats caused deficits in cognition but no changes in social play or interaction. Preliminary data on the anatomy of the brains showed no structural differences in brain regions related to social behavior and cognition. These findings suggest that early, mild hearing loss is sufficient to cause cognitive impairment in the absence of overt structural changes in related brain regions. More detailed molecular analyses are ongoing to examine what specific mechanisms are contributing to the observed cognitive deficit in the current model.

The previous data was presented at the meeting of the Association for Research in Otolaryngology, the BCN symposium and the Dutch Neuroscience Meeting. At the BCN symposium Joëlle received a poster prize. Future work will use a similar design to compare the behavioral, cognitive, and neurobiological consequences of permanent and temporary hearing loss. More extensive behavioral phenotyping of the models will be made possible due to additional funding we received for equipment to record and play back rodent vocalizations.