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Accueil > Alexandra GOURLAN



Rechercher

OSUG - Terre Univers Environnement

GOURLAN Alexandra

  • Statut : Chercheur
  • Grade : Maître de conférences
  • Tutelle : UGA
  • Bureau : 307
  • Téléphone : +33 (0)4 76 63 59 13
  • Localisation : Grenoble
  • Courriel : Contactez moi
  • Equipe de recherche / Service : Géochimie

My research focuses on Two main topics, which are all based on isotopic geochemistry :

1) PAST CLIMATE AND OCEANIC RECONSTITUTIONS.
I’m working principally on the erosion-climate-sedimentary record links through the Quaternary period.

Time relationships between climate change and erosion of high reliefs is a matter of debate.
The Bengal Gulf and Arabian Sea are very attractive case to understand this relationship because the Himalayas (the largest modern orogenic belt) and the Asian monsoon phenomenon (one of the largest climatic phenomenon) coexist in the same region. In theses gigantic fans are accumulated the sediments eroded from the Himalayan mountain range. So, they represent an archive of the Himalayan erosion through time. The study of the marine sediments in the Bengal Gulf and Arabian Sea appears therefore as an ideal target to understand the relationship between the Himalayan erosion, the Indian Monsoon regime and the marine sedimentary record.
To study the influence of climatic parameters on the external geodynamic process and ocean dynamics during the quaternary period, radiogenic isotopes are very precious tools because of their high sensibility. These isotopic tracers (Nd, Pb, Sr, …) as tracers of source allow a better understanding of the direction of the past winds, the continental erosion, the oceanic paleocirculation and the climate (Revel-Rolland and al., on 2005 ; Tütken and al., on 2006 ; Placzek and al., on 2011 ; Grousset and al., on 1988 ; France-Lanord and al, on 1993 ; Derry and France-Lanord, on 1996 ; Abouchami W. and al., on 2003 ; Gourlan and al., on 2008).

Some publications
K. Tachikawa, T. Arsouze, G. Bayon, A. Bory, C. Colin, J-C Dutay, N. Frank, X. Giraud, A.T. Gourlan, C. Jeandel, F. Lacan, L. Meynadier, P. Montagn, P. Montagna, E. Puceat, M. Roy-Barman and C. Waelbroeck. The large-scale evolution of neodymium isotopic composition in the global modern and Holocene ocean revealed from seawater and archive data . Chemical Geology, Elsevier, 2017, in press.
Achyuthan, H. Nagasundaram, M., Gourlan, A.T., Eastoe, C., Ahmad, S. M., Padmakumari, V. M., 2014. Mid-Holocene Indian Summer Monsoon variability off the Andaman Islands, Bay of Bengal. Quaternary International, 349, 232–244.
J. Braun, C. Voisin, A. T. Gourlan, and C. Chauvel, 2015. Erosional response of an actively uplifting mountain belt to cyclic rainfall variations. Earth Surf. Dynam., 3, 1–14
A.T. Gourlan, L. Meynadier, C. J. Allègre. 2010. Northern hemisphere climate control of the bengali rivers discharge during the last 4 Ma. Quaternary Science Reviews 29 : 2484-2498

2) GEOCHEMISTRY APPLIED ON HEALTH SCIENCES
I’m working principally in collaboration with ENS-Lyon, Vetagro-Sup and Zoo of Lyon on the animal metabolism by using the stable isotopes of metals.

The copper is a micronutrient involved in numerous physiological processes also occurring in key mechanisms of the cancerogenesis and tumor progression (Denoyer et al, 2015). Several studies made on cancerous patients tend to show a disturbance of the metabolism of the copper and, a recent study shows that the patients dying from a colorectal cancer or from a breast cancer presented a significant decrease of the ratio between the two stable isotopes of the copper 65Cu / 63Cu (δ Cu) compared with healthy controls (Telouk et al, 2015). The mechanism at the origin of this decrease is unknown but it could be due to the preferential chelation of 65Cu by the lactate produced in great quantities by the tumor. Contrary to "healthy" patients, the lightest isotopes of the Copper pass preferentially in the serum during their departure of the body and the heaviest isotopes stay in the cell. With a turnover in the body of 4 to 6 weeks, Copper can be a potential biomarker to discriminate un-affected and affected persons and can be used to track cancer progression by monitoring cancer.

Some publications :
G. Chamel, A. T. Gourlan, P. Télouk, D. Sayag, V. Milliard, C. Loiseau, S. Buff, F. Ponce , 2016. Retrospective evaluation of blood copper stable isotopes ratio 65Cu/63Cu as a biomarker of cancer in dogs. Journal of Veterinary and Comparative Oncology. DOI : 10.1111/vco.12273



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