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Abstract title Histone acetylation modifications in the circadian shedding rhythm of Schistosoma mansoni cercariae
Author Hélène Moné, IHPE, UMR 5244, Perpignan, France (Presenting author)
Co-author(s) Gabriel Mouahid, IHPE, UMR 5244, Perpignan, France
Jean-François Allienne, IHPE, UMR 5244, Perpignan, France
Khalid Al-Mushaikhi, Directorate General of Health Services, Dhofar Governorate, Ministry of Health, Salalah, Oman
Saalem Al-Yafae, Directorate General of Health Services, Dhofar Governorate, Ministry of Health, Salalah, Oman
David Duval, IHPE, UMR 5244, Perpignan, France
Richard Galinier, IHPE, UMR 5244, Perpignan, France
Guillaume Mitta, IHPE, UMR 5244, Perpignan, France
Guillaume Tetreau, IHPE, UMR 5244, Perpignan, France
Andre Theron, IHPE, UMR 5244, Perpignan, France
Anne Rognon, IHPE, UMR 5244, Perpignan, France
Christoph Grunau, IHPE, UMR 5244, Perpignan, France
Topic 6. Evolutionary significance of biological clocks
Abstract text

Circadian rhythms govern diurnal variations in physiological functions and are synchronized by 24-h cyclic signals with light being often the main external cue (“Zeitgeber”). At the molecular level, in many species circadian clocks involve periodic changes in the expression of a canonical set of clock genes but involve also post-translational histone modifications. Schistosomes are important human parasites that cause Bilharziasis. Their reservoir hosts are rodents. Infective larvae (cercariae) are produced in vector snails and released into fresh water at specific time points corresponding to the principal activity of the vertebrate hosts: 12 AM for human hosts, 8 PM for rodents hosts. We show that the timing of cercarial shedding is not correlated with canonical clock gene expression but can be linked to modifications of H3K9/H3K14 acetylation. A Hidden Markov Model (HMM)-based approach identified 107 differentially acetylated regions containing 61 candidate genes of which at least 14 (23%) can be related to the control and establishment of circadian rhythm. This suggests a flexible histone acetylation based phasing mechanism for circadian shedding of Schistosoma mansoni cercariae that allows for rapid adaptation to host behavior. The zeitgeber for this system and its genetic determinants remain to be discovered.