Majdulin Istiban wint als eerste buitenlandse student de PDL-prijs voor beste masterthesis biologie

De examencommissies hebben weer hun werk gedaan en dat betekent dat we weten wie dit academiejaar de PDL-prijs voor de beste masterthesis biologie, inclusief vijf briefjes van 50 euro, in ontvangst mag nemen. Voor de eerste keer in de geschiedenis van de prijzen gaat die naar een buitenlandse student in de Master of Biology. Proficiat, Majdulin Istiban! Hieronder beschrijft Majdulin het onderzoek in het kader van haar masterthesis.

Katholieke Universiteit Leuven and its Faculty of Science provided a challenging and enriching environment for my graduate studies, despite the extenuating circumstances involving remote work and safely limited social interactions due to COVID. I particularly enjoyed the course “Critical discussions in molecular biology and physiology” led by Prof. Eve Seuntjens, which involved the active dissemination and analysis of journal articles with their authors and other subject matter experts.

As part of my thesis project, I joined the labs of Prof. William Schafer (Genetic and Neurochemical Basis of Behavior) and Prof. Isabel Beets (Neural Signaling and Circuit Plasticity). Using the small 1-mm Caenorhabditis elegans worm as a model organism, both labs investigate the regulation of arousal by the nervous system. This is a behavioral state that allows organisms to escape threatening situations by becoming faster and more alert. The increase in sensory alertness is referred to as sensitization.

Figure: Head neurons in C. elegans expressing flp-7 (left) and npr-13 (right), labeled with a green fluorescent protein, GFP. (Image credit: Keertana Venkatesh. Beets lab, KU Leuven) Despite their small size and compact nervous system, C. elegans can perceive and respond to a variety of stimuli, including touch, chemicals, humidity, vibrations, different gases, and more. If exposed to a noxious cue (tapping their container), C. elegans exhibit increased speed for around two minutes and are primed to a specific chemical called glycerol. This behavioral state was previously explored in Prof. Schafer’s lab with an emphasis on the regulatory role of neuropeptides. These neuropeptides act as chemical signals by binding to receptor proteins on the surface of target cells. This includes the neuropeptide flp-7 and the receptor npr-13, which appear to be involved in glycerol response sensitization after taps. The important distinction is that these neuropeptide candidates do not appear to affect acceleration, and only influence sensitization to glycerol. Testing this theory involved stimulating worms where flp-7 or npr-13 were mutated and not functional. If these candidates were actually required for arousal, their absence would impair C. elegans’ response. My project involved verifying that acceleration is not regulated by these candidates; preliminary data corroborates that neither candidate is required for increased speed after plate taps.

Another noxious stimulus for C. elegans is the atmospheric oxygen level. This serves as an indicator for surface exposure, implying a higher chance of predation. To escape this unfavorable environment, worms speed up until they find more suitable conditions. We tested whether our gene candidates may also be involved in acceleration relative to ambient oxygen levels. Our data suggest a potential role for flp-7 in this escape response but not npr-13. More detailed experiments will seek to further define the roles of flp-7 and npr-13 in arousal and oxygen-induced escape responses. Better understanding the cellular, molecular, and regulatory basis of arousal through smaller discoveries like these could unlock new tools for manipulating the level of alertness of organisms.

Majdulin Nabil Istiban

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