17/04/2021

Adaptation to a seasonal word: study of the mechanisms underlying photorefractoriness


  • ORGANISATION/COMPANY
    UMR CNRS/MNHN 7179
  • RESEARCH FIELD
    Biological sciencesBiology
    Environmental scienceEcology
    Psychological sciencesPsychology
  • RESEARCHER PROFILE
    First Stage Researcher (R1)
    Recognised Researcher (R2)
    Established Researcher (R3)
    Leading Researcher (R4)
  • APPLICATION DEADLINE
    26/05/2021 00:00 - Europe/Brussels
  • LOCATION
    France › Brunoy
  • TYPE OF CONTRACT
    Temporary
  • JOB STATUS
    Full-time
  • OFFER STARTING DATE
    04/10/2021

OFFER DESCRIPTION

Main PhD supervisor: Dr Fabienne Aujard
Secondary PhD supervisor: Dr Jérémy Terrien

The French research unit UMR 7179 is offering an opportunity to defend a PhD scholarship to be attributed by the Museum National d’Histoire Naturelle (ED227) in July 2021 (PhD to start in October 2021. The applicant will defend a subject entitled “Adaptation to a seasonal word: study of the mechanisms underlying photorefractoriness”.

The synchronization of biological functions with annual variations in environmental conditions is an essential condition for survival, making the ‘measurement’ of time crucial. Seasonal species use the photoperiod as a clue of chronological time, this parameter being integrated at the central level. The induced neuroendocrine regulations, notably involving thyroid hormones (THs), are relatively well described, unlike the mechanisms governing the temporality of these regulations. While the mechanisms involved in circadian rhythmicity, characterized by post-transcriptional regulatory loops, are well known1, those governing circannual rhythms, and in particular the phenomenon of resistance to photoperiod change, also called photorefractoriness, are still unknown. In addition, it seems that the ‘measure’ of seasonal time differs between species, and even by sex within the same species, probably due to discrepancies in the life history traits of each organism.

Mechanistically, the integration of the photoperiod occurs through the secretion of melatonin by the pineal gland, its duration of secretion varying with the length of the night2. Recent work has demonstrated the crucial role of intra-hypothalamic availability in THs in the melatoninergic regulation of reproductive and metabolic functions3. This effect is thought to be mediated by tanycytes, particular glial cells, which line the wall of the third ventricle in the hypothalamus, and which are known to be involved in the central control of reproduction, food intake and energy homeostasis4. Thus, the photoperiod, via melatonin, regulates the production of intra-hypothalamic HTs by tanycytes, which could participate in the seasonal regulation of neuronal circuits involved in the control of reproduction and metabolism. This PhD project therefore aims to describe the mechanisms involved in the phenomenon of photorefractoriness in a seasonal primate, the mouse lemur (Microcebus murinus), which seasonality is differently expressed between males and females. The objectives of this project are to decipher the mechanisms regulating photorefractoriness, to what extent they differ between males and females, but also to assess the role of HTs in this process.

Ultimately, the results of this work could help to better anticipate the impact of global warming on the synchronization of organisms with the environment. Indeed, the risk of desynchronization between seasonal variations in ambient temperature and photoperiod2, in addition to the increased frequency of unpredictable climatic events, could lead to maladaptive responses for strictly seasonal species5.

 

References :

1. Ko & Takahashi. Hum. Mol. Genet. 15 Spec No 2, (2006). 2. Hut & Beersma. Philos. Trans. R. Soc. Lond. B Biol. Sci. 366, (2011). 3. Quignon et al. FASEB J. 34, (2020). 4. Prevot et al. Endocr. Rev., (2018). 5. Landes et al. Frontiers in Physiology 11, (2020).



Funding category: Contrat doctoral

The scholarship is not secured; the selected candidate will defend the subject at the Doctoral School in July 2021 to obtain the scholarship

PHD Country: France

More Information

Offer Requirements

Specific Requirements

Applicants must be highly motivated and have a strong interest in our scientific area (for more information, please visit our website at http://www.mecadev.cnrs.fr/). A strong background of basic molecular research methodology (e.g. IHC, gene expression analysis) are mandatory. Given the scope of this subject, a strong background in physiology and biology of adaptation would be appreciated. Finally, a strong academic background, with high-level academic records, is mandatory.

Map Information

Job Work Location Personal Assistance locations
Work location(s)
1 position(s) available at
UMR CNRS/MNHN 7179
France
Brunoy

EURAXESS offer ID: 630137
Posting organisation offer ID: 97607

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